Changed from static to 11ty!

6 files changed, 3266 insertions, 0 deletions

diff --git a/node_modules/commander/lib/argument.js b/node_modules/commander/lib/argument.js
new file mode 100644
index 0000000..c164302
--- /dev/null
+++ b/node_modules/commander/lib/argument.js
@@ -0,0 +1,147 @@
+const { InvalidArgumentError } = require('./error.js');
+
+// @ts-check
+
+class Argument {
+  /**
+   * Initialize a new command argument with the given name and description.
+   * The default is that the argument is required, and you can explicitly
+   * indicate this with <> around the name. Put [] around the name for an optional argument.
+   *
+   * @param {string} name
+   * @param {string} [description]
+   */
+
+  constructor(name, description) {
+    this.description = description || '';
+    this.variadic = false;
+    this.parseArg = undefined;
+    this.defaultValue = undefined;
+    this.defaultValueDescription = undefined;
+    this.argChoices = undefined;
+
+    switch (name[0]) {
+      case '<': // e.g. <required>
+        this.required = true;
+        this._name = name.slice(1, -1);
+        break;
+      case '[': // e.g. [optional]
+        this.required = false;
+        this._name = name.slice(1, -1);
+        break;
+      default:
+        this.required = true;
+        this._name = name;
+        break;
+    }
+
+    if (this._name.length > 3 && this._name.slice(-3) === '...') {
+      this.variadic = true;
+      this._name = this._name.slice(0, -3);
+    }
+  }
+
+  /**
+   * Return argument name.
+   *
+   * @return {string}
+   */
+
+  name() {
+    return this._name;
+  }
+
+  /**
+   * @api private
+   */
+
+  _concatValue(value, previous) {
+    if (previous === this.defaultValue || !Array.isArray(previous)) {
+      return [value];
+    }
+
+    return previous.concat(value);
+  }
+
+  /**
+   * Set the default value, and optionally supply the description to be displayed in the help.
+   *
+   * @param {any} value
+   * @param {string} [description]
+   * @return {Argument}
+   */
+
+  default(value, description) {
+    this.defaultValue = value;
+    this.defaultValueDescription = description;
+    return this;
+  }
+
+  /**
+   * Set the custom handler for processing CLI command arguments into argument values.
+   *
+   * @param {Function} [fn]
+   * @return {Argument}
+   */
+
+  argParser(fn) {
+    this.parseArg = fn;
+    return this;
+  }
+
+  /**
+   * Only allow argument value to be one of choices.
+   *
+   * @param {string[]} values
+   * @return {Argument}
+   */
+
+  choices(values) {
+    this.argChoices = values.slice();
+    this.parseArg = (arg, previous) => {
+      if (!this.argChoices.includes(arg)) {
+        throw new InvalidArgumentError(`Allowed choices are ${this.argChoices.join(', ')}.`);
+      }
+      if (this.variadic) {
+        return this._concatValue(arg, previous);
+      }
+      return arg;
+    };
+    return this;
+  }
+
+  /**
+   * Make argument required.
+   */
+  argRequired() {
+    this.required = true;
+    return this;
+  }
+
+  /**
+   * Make argument optional.
+   */
+  argOptional() {
+    this.required = false;
+    return this;
+  }
+}
+
+/**
+ * Takes an argument and returns its human readable equivalent for help usage.
+ *
+ * @param {Argument} arg
+ * @return {string}
+ * @api private
+ */
+
+function humanReadableArgName(arg) {
+  const nameOutput = arg.name() + (arg.variadic === true ? '...' : '');
+
+  return arg.required
+    ? '<' + nameOutput + '>'
+    : '[' + nameOutput + ']';
+}
+
+exports.Argument = Argument;
+exports.humanReadableArgName = humanReadableArgName;
diff --git a/node_modules/commander/lib/command.js b/node_modules/commander/lib/command.js
new file mode 100644
index 0000000..7a637cb
--- /dev/null
+++ b/node_modules/commander/lib/command.js
@@ -0,0 +1,2179 @@
+const EventEmitter = require('events').EventEmitter;
+const childProcess = require('child_process');
+const path = require('path');
+const fs = require('fs');
+const process = require('process');
+
+const { Argument, humanReadableArgName } = require('./argument.js');
+const { CommanderError } = require('./error.js');
+const { Help } = require('./help.js');
+const { Option, splitOptionFlags, DualOptions } = require('./option.js');
+const { suggestSimilar } = require('./suggestSimilar');
+
+// @ts-check
+
+class Command extends EventEmitter {
+  /**
+   * Initialize a new `Command`.
+   *
+   * @param {string} [name]
+   */
+
+  constructor(name) {
+    super();
+    /** @type {Command[]} */
+    this.commands = [];
+    /** @type {Option[]} */
+    this.options = [];
+    this.parent = null;
+    this._allowUnknownOption = false;
+    this._allowExcessArguments = true;
+    /** @type {Argument[]} */
+    this._args = [];
+    /** @type {string[]} */
+    this.args = []; // cli args with options removed
+    this.rawArgs = [];
+    this.processedArgs = []; // like .args but after custom processing and collecting variadic
+    this._scriptPath = null;
+    this._name = name || '';
+    this._optionValues = {};
+    this._optionValueSources = {}; // default, env, cli etc
+    this._storeOptionsAsProperties = false;
+    this._actionHandler = null;
+    this._executableHandler = false;
+    this._executableFile = null; // custom name for executable
+    this._executableDir = null; // custom search directory for subcommands
+    this._defaultCommandName = null;
+    this._exitCallback = null;
+    this._aliases = [];
+    this._combineFlagAndOptionalValue = true;
+    this._description = '';
+    this._summary = '';
+    this._argsDescription = undefined; // legacy
+    this._enablePositionalOptions = false;
+    this._passThroughOptions = false;
+    this._lifeCycleHooks = {}; // a hash of arrays
+    /** @type {boolean | string} */
+    this._showHelpAfterError = false;
+    this._showSuggestionAfterError = true;
+
+    // see .configureOutput() for docs
+    this._outputConfiguration = {
+      writeOut: (str) => process.stdout.write(str),
+      writeErr: (str) => process.stderr.write(str),
+      getOutHelpWidth: () => process.stdout.isTTY ? process.stdout.columns : undefined,
+      getErrHelpWidth: () => process.stderr.isTTY ? process.stderr.columns : undefined,
+      outputError: (str, write) => write(str)
+    };
+
+    this._hidden = false;
+    this._hasHelpOption = true;
+    this._helpFlags = '-h, --help';
+    this._helpDescription = 'display help for command';
+    this._helpShortFlag = '-h';
+    this._helpLongFlag = '--help';
+    this._addImplicitHelpCommand = undefined; // Deliberately undefined, not decided whether true or false
+    this._helpCommandName = 'help';
+    this._helpCommandnameAndArgs = 'help [command]';
+    this._helpCommandDescription = 'display help for command';
+    this._helpConfiguration = {};
+  }
+
+  /**
+   * Copy settings that are useful to have in common across root command and subcommands.
+   *
+   * (Used internally when adding a command using `.command()` so subcommands inherit parent settings.)
+   *
+   * @param {Command} sourceCommand
+   * @return {Command} `this` command for chaining
+   */
+  copyInheritedSettings(sourceCommand) {
+    this._outputConfiguration = sourceCommand._outputConfiguration;
+    this._hasHelpOption = sourceCommand._hasHelpOption;
+    this._helpFlags = sourceCommand._helpFlags;
+    this._helpDescription = sourceCommand._helpDescription;
+    this._helpShortFlag = sourceCommand._helpShortFlag;
+    this._helpLongFlag = sourceCommand._helpLongFlag;
+    this._helpCommandName = sourceCommand._helpCommandName;
+    this._helpCommandnameAndArgs = sourceCommand._helpCommandnameAndArgs;
+    this._helpCommandDescription = sourceCommand._helpCommandDescription;
+    this._helpConfiguration = sourceCommand._helpConfiguration;
+    this._exitCallback = sourceCommand._exitCallback;
+    this._storeOptionsAsProperties = sourceCommand._storeOptionsAsProperties;
+    this._combineFlagAndOptionalValue = sourceCommand._combineFlagAndOptionalValue;
+    this._allowExcessArguments = sourceCommand._allowExcessArguments;
+    this._enablePositionalOptions = sourceCommand._enablePositionalOptions;
+    this._showHelpAfterError = sourceCommand._showHelpAfterError;
+    this._showSuggestionAfterError = sourceCommand._showSuggestionAfterError;
+
+    return this;
+  }
+
+  /**
+   * Define a command.
+   *
+   * There are two styles of command: pay attention to where to put the description.
+   *
+   * @example
+   * // Command implemented using action handler (description is supplied separately to `.command`)
+   * program
+   *   .command('clone <source> [destination]')
+   *   .description('clone a repository into a newly created directory')
+   *   .action((source, destination) => {
+   *     console.log('clone command called');
+   *   });
+   *
+   * // Command implemented using separate executable file (description is second parameter to `.command`)
+   * program
+   *   .command('start <service>', 'start named service')
+   *   .command('stop [service]', 'stop named service, or all if no name supplied');
+   *
+   * @param {string} nameAndArgs - command name and arguments, args are `<required>` or `[optional]` and last may also be `variadic...`
+   * @param {Object|string} [actionOptsOrExecDesc] - configuration options (for action), or description (for executable)
+   * @param {Object} [execOpts] - configuration options (for executable)
+   * @return {Command} returns new command for action handler, or `this` for executable command
+   */
+
+  command(nameAndArgs, actionOptsOrExecDesc, execOpts) {
+    let desc = actionOptsOrExecDesc;
+    let opts = execOpts;
+    if (typeof desc === 'object' && desc !== null) {
+      opts = desc;
+      desc = null;
+    }
+    opts = opts || {};
+    const [, name, args] = nameAndArgs.match(/([^ ]+) *(.*)/);
+
+    const cmd = this.createCommand(name);
+    if (desc) {
+      cmd.description(desc);
+      cmd._executableHandler = true;
+    }
+    if (opts.isDefault) this._defaultCommandName = cmd._name;
+    cmd._hidden = !!(opts.noHelp || opts.hidden); // noHelp is deprecated old name for hidden
+    cmd._executableFile = opts.executableFile || null; // Custom name for executable file, set missing to null to match constructor
+    if (args) cmd.arguments(args);
+    this.commands.push(cmd);
+    cmd.parent = this;
+    cmd.copyInheritedSettings(this);
+
+    if (desc) return this;
+    return cmd;
+  }
+
+  /**
+   * Factory routine to create a new unattached command.
+   *
+   * See .command() for creating an attached subcommand, which uses this routine to
+   * create the command. You can override createCommand to customise subcommands.
+   *
+   * @param {string} [name]
+   * @return {Command} new command
+   */
+
+  createCommand(name) {
+    return new Command(name);
+  }
+
+  /**
+   * You can customise the help with a subclass of Help by overriding createHelp,
+   * or by overriding Help properties using configureHelp().
+   *
+   * @return {Help}
+   */
+
+  createHelp() {
+    return Object.assign(new Help(), this.configureHelp());
+  }
+
+  /**
+   * You can customise the help by overriding Help properties using configureHelp(),
+   * or with a subclass of Help by overriding createHelp().
+   *
+   * @param {Object} [configuration] - configuration options
+   * @return {Command|Object} `this` command for chaining, or stored configuration
+   */
+
+  configureHelp(configuration) {
+    if (configuration === undefined) return this._helpConfiguration;
+
+    this._helpConfiguration = configuration;
+    return this;
+  }
+
+  /**
+   * The default output goes to stdout and stderr. You can customise this for special
+   * applications. You can also customise the display of errors by overriding outputError.
+   *
+   * The configuration properties are all functions:
+   *
+   *     // functions to change where being written, stdout and stderr
+   *     writeOut(str)
+   *     writeErr(str)
+   *     // matching functions to specify width for wrapping help
+   *     getOutHelpWidth()
+   *     getErrHelpWidth()
+   *     // functions based on what is being written out
+   *     outputError(str, write) // used for displaying errors, and not used for displaying help
+   *
+   * @param {Object} [configuration] - configuration options
+   * @return {Command|Object} `this` command for chaining, or stored configuration
+   */
+
+  configureOutput(configuration) {
+    if (configuration === undefined) return this._outputConfiguration;
+
+    Object.assign(this._outputConfiguration, configuration);
+    return this;
+  }
+
+  /**
+   * Display the help or a custom message after an error occurs.
+   *
+   * @param {boolean|string} [displayHelp]
+   * @return {Command} `this` command for chaining
+   */
+  showHelpAfterError(displayHelp = true) {
+    if (typeof displayHelp !== 'string') displayHelp = !!displayHelp;
+    this._showHelpAfterError = displayHelp;
+    return this;
+  }
+
+  /**
+   * Display suggestion of similar commands for unknown commands, or options for unknown options.
+   *
+   * @param {boolean} [displaySuggestion]
+   * @return {Command} `this` command for chaining
+   */
+  showSuggestionAfterError(displaySuggestion = true) {
+    this._showSuggestionAfterError = !!displaySuggestion;
+    return this;
+  }
+
+  /**
+   * Add a prepared subcommand.
+   *
+   * See .command() for creating an attached subcommand which inherits settings from its parent.
+   *
+   * @param {Command} cmd - new subcommand
+   * @param {Object} [opts] - configuration options
+   * @return {Command} `this` command for chaining
+   */
+
+  addCommand(cmd, opts) {
+    if (!cmd._name) {
+      throw new Error(`Command passed to .addCommand() must have a name
+- specify the name in Command constructor or using .name()`);
+    }
+
+    opts = opts || {};
+    if (opts.isDefault) this._defaultCommandName = cmd._name;
+    if (opts.noHelp || opts.hidden) cmd._hidden = true; // modifying passed command due to existing implementation
+
+    this.commands.push(cmd);
+    cmd.parent = this;
+    return this;
+  }
+
+  /**
+   * Factory routine to create a new unattached argument.
+   *
+   * See .argument() for creating an attached argument, which uses this routine to
+   * create the argument. You can override createArgument to return a custom argument.
+   *
+   * @param {string} name
+   * @param {string} [description]
+   * @return {Argument} new argument
+   */
+
+  createArgument(name, description) {
+    return new Argument(name, description);
+  }
+
+  /**
+   * Define argument syntax for command.
+   *
+   * The default is that the argument is required, and you can explicitly
+   * indicate this with <> around the name. Put [] around the name for an optional argument.
+   *
+   * @example
+   * program.argument('<input-file>');
+   * program.argument('[output-file]');
+   *
+   * @param {string} name
+   * @param {string} [description]
+   * @param {Function|*} [fn] - custom argument processing function
+   * @param {*} [defaultValue]
+   * @return {Command} `this` command for chaining
+   */
+  argument(name, description, fn, defaultValue) {
+    const argument = this.createArgument(name, description);
+    if (typeof fn === 'function') {
+      argument.default(defaultValue).argParser(fn);
+    } else {
+      argument.default(fn);
+    }
+    this.addArgument(argument);
+    return this;
+  }
+
+  /**
+   * Define argument syntax for command, adding multiple at once (without descriptions).
+   *
+   * See also .argument().
+   *
+   * @example
+   * program.arguments('<cmd> [env]');
+   *
+   * @param {string} names
+   * @return {Command} `this` command for chaining
+   */
+
+  arguments(names) {
+    names.split(/ +/).forEach((detail) => {
+      this.argument(detail);
+    });
+    return this;
+  }
+
+  /**
+   * Define argument syntax for command, adding a prepared argument.
+   *
+   * @param {Argument} argument
+   * @return {Command} `this` command for chaining
+   */
+  addArgument(argument) {
+    const previousArgument = this._args.slice(-1)[0];
+    if (previousArgument && previousArgument.variadic) {
+      throw new Error(`only the last argument can be variadic '${previousArgument.name()}'`);
+    }
+    if (argument.required && argument.defaultValue !== undefined && argument.parseArg === undefined) {
+      throw new Error(`a default value for a required argument is never used: '${argument.name()}'`);
+    }
+    this._args.push(argument);
+    return this;
+  }
+
+  /**
+   * Override default decision whether to add implicit help command.
+   *
+   *    addHelpCommand() // force on
+   *    addHelpCommand(false); // force off
+   *    addHelpCommand('help [cmd]', 'display help for [cmd]'); // force on with custom details
+   *
+   * @return {Command} `this` command for chaining
+   */
+
+  addHelpCommand(enableOrNameAndArgs, description) {
+    if (enableOrNameAndArgs === false) {
+      this._addImplicitHelpCommand = false;
+    } else {
+      this._addImplicitHelpCommand = true;
+      if (typeof enableOrNameAndArgs === 'string') {
+        this._helpCommandName = enableOrNameAndArgs.split(' ')[0];
+        this._helpCommandnameAndArgs = enableOrNameAndArgs;
+      }
+      this._helpCommandDescription = description || this._helpCommandDescription;
+    }
+    return this;
+  }
+
+  /**
+   * @return {boolean}
+   * @api private
+   */
+
+  _hasImplicitHelpCommand() {
+    if (this._addImplicitHelpCommand === undefined) {
+      return this.commands.length && !this._actionHandler && !this._findCommand('help');
+    }
+    return this._addImplicitHelpCommand;
+  }
+
+  /**
+   * Add hook for life cycle event.
+   *
+   * @param {string} event
+   * @param {Function} listener
+   * @return {Command} `this` command for chaining
+   */
+
+  hook(event, listener) {
+    const allowedValues = ['preSubcommand', 'preAction', 'postAction'];
+    if (!allowedValues.includes(event)) {
+      throw new Error(`Unexpected value for event passed to hook : '${event}'.
+Expecting one of '${allowedValues.join("', '")}'`);
+    }
+    if (this._lifeCycleHooks[event]) {
+      this._lifeCycleHooks[event].push(listener);
+    } else {
+      this._lifeCycleHooks[event] = [listener];
+    }
+    return this;
+  }
+
+  /**
+   * Register callback to use as replacement for calling process.exit.
+   *
+   * @param {Function} [fn] optional callback which will be passed a CommanderError, defaults to throwing
+   * @return {Command} `this` command for chaining
+   */
+
+  exitOverride(fn) {
+    if (fn) {
+      this._exitCallback = fn;
+    } else {
+      this._exitCallback = (err) => {
+        if (err.code !== 'commander.executeSubCommandAsync') {
+          throw err;
+        } else {
+          // Async callback from spawn events, not useful to throw.
+        }
+      };
+    }
+    return this;
+  }
+
+  /**
+   * Call process.exit, and _exitCallback if defined.
+   *
+   * @param {number} exitCode exit code for using with process.exit
+   * @param {string} code an id string representing the error
+   * @param {string} message human-readable description of the error
+   * @return never
+   * @api private
+   */
+
+  _exit(exitCode, code, message) {
+    if (this._exitCallback) {
+      this._exitCallback(new CommanderError(exitCode, code, message));
+      // Expecting this line is not reached.
+    }
+    process.exit(exitCode);
+  }
+
+  /**
+   * Register callback `fn` for the command.
+   *
+   * @example
+   * program
+   *   .command('serve')
+   *   .description('start service')
+   *   .action(function() {
+   *      // do work here
+   *   });
+   *
+   * @param {Function} fn
+   * @return {Command} `this` command for chaining
+   */
+
+  action(fn) {
+    const listener = (args) => {
+      // The .action callback takes an extra parameter which is the command or options.
+      const expectedArgsCount = this._args.length;
+      const actionArgs = args.slice(0, expectedArgsCount);
+      if (this._storeOptionsAsProperties) {
+        actionArgs[expectedArgsCount] = this; // backwards compatible "options"
+      } else {
+        actionArgs[expectedArgsCount] = this.opts();
+      }
+      actionArgs.push(this);
+
+      return fn.apply(this, actionArgs);
+    };
+    this._actionHandler = listener;
+    return this;
+  }
+
+  /**
+   * Factory routine to create a new unattached option.
+   *
+   * See .option() for creating an attached option, which uses this routine to
+   * create the option. You can override createOption to return a custom option.
+   *
+   * @param {string} flags
+   * @param {string} [description]
+   * @return {Option} new option
+   */
+
+  createOption(flags, description) {
+    return new Option(flags, description);
+  }
+
+  /**
+   * Add an option.
+   *
+   * @param {Option} option
+   * @return {Command} `this` command for chaining
+   */
+  addOption(option) {
+    const oname = option.name();
+    const name = option.attributeName();
+
+    // store default value
+    if (option.negate) {
+      // --no-foo is special and defaults foo to true, unless a --foo option is already defined
+      const positiveLongFlag = option.long.replace(/^--no-/, '--');
+      if (!this._findOption(positiveLongFlag)) {
+        this.setOptionValueWithSource(name, option.defaultValue === undefined ? true : option.defaultValue, 'default');
+      }
+    } else if (option.defaultValue !== undefined) {
+      this.setOptionValueWithSource(name, option.defaultValue, 'default');
+    }
+
+    // register the option
+    this.options.push(option);
+
+    // handler for cli and env supplied values
+    const handleOptionValue = (val, invalidValueMessage, valueSource) => {
+      // val is null for optional option used without an optional-argument.
+      // val is undefined for boolean and negated option.
+      if (val == null && option.presetArg !== undefined) {
+        val = option.presetArg;
+      }
+
+      // custom processing
+      const oldValue = this.getOptionValue(name);
+      if (val !== null && option.parseArg) {
+        try {
+          val = option.parseArg(val, oldValue);
+        } catch (err) {
+          if (err.code === 'commander.invalidArgument') {
+            const message = `${invalidValueMessage} ${err.message}`;
+            this.error(message, { exitCode: err.exitCode, code: err.code });
+          }
+          throw err;
+        }
+      } else if (val !== null && option.variadic) {
+        val = option._concatValue(val, oldValue);
+      }
+
+      // Fill-in appropriate missing values. Long winded but easy to follow.
+      if (val == null) {
+        if (option.negate) {
+          val = false;
+        } else if (option.isBoolean() || option.optional) {
+          val = true;
+        } else {
+          val = ''; // not normal, parseArg might have failed or be a mock function for testing
+        }
+      }
+      this.setOptionValueWithSource(name, val, valueSource);
+    };
+
+    this.on('option:' + oname, (val) => {
+      const invalidValueMessage = `error: option '${option.flags}' argument '${val}' is invalid.`;
+      handleOptionValue(val, invalidValueMessage, 'cli');
+    });
+
+    if (option.envVar) {
+      this.on('optionEnv:' + oname, (val) => {
+        const invalidValueMessage = `error: option '${option.flags}' value '${val}' from env '${option.envVar}' is invalid.`;
+        handleOptionValue(val, invalidValueMessage, 'env');
+      });
+    }
+
+    return this;
+  }
+
+  /**
+   * Internal implementation shared by .option() and .requiredOption()
+   *
+   * @api private
+   */
+  _optionEx(config, flags, description, fn, defaultValue) {
+    if (typeof flags === 'object' && flags instanceof Option) {
+      throw new Error('To add an Option object use addOption() instead of option() or requiredOption()');
+    }
+    const option = this.createOption(flags, description);
+    option.makeOptionMandatory(!!config.mandatory);
+    if (typeof fn === 'function') {
+      option.default(defaultValue).argParser(fn);
+    } else if (fn instanceof RegExp) {
+      // deprecated
+      const regex = fn;
+      fn = (val, def) => {
+        const m = regex.exec(val);
+        return m ? m[0] : def;
+      };
+      option.default(defaultValue).argParser(fn);
+    } else {
+      option.default(fn);
+    }
+
+    return this.addOption(option);
+  }
+
+  /**
+   * Define option with `flags`, `description` and optional
+   * coercion `fn`.
+   *
+   * The `flags` string contains the short and/or long flags,
+   * separated by comma, a pipe or space. The following are all valid
+   * all will output this way when `--help` is used.
+   *
+   *     "-p, --pepper"
+   *     "-p|--pepper"
+   *     "-p --pepper"
+   *
+   * @example
+   * // simple boolean defaulting to undefined
+   * program.option('-p, --pepper', 'add pepper');
+   *
+   * program.pepper
+   * // => undefined
+   *
+   * --pepper
+   * program.pepper
+   * // => true
+   *
+   * // simple boolean defaulting to true (unless non-negated option is also defined)
+   * program.option('-C, --no-cheese', 'remove cheese');
+   *
+   * program.cheese
+   * // => true
+   *
+   * --no-cheese
+   * program.cheese
+   * // => false
+   *
+   * // required argument
+   * program.option('-C, --chdir <path>', 'change the working directory');
+   *
+   * --chdir /tmp
+   * program.chdir
+   * // => "/tmp"
+   *
+   * // optional argument
+   * program.option('-c, --cheese [type]', 'add cheese [marble]');
+   *
+   * @param {string} flags
+   * @param {string} [description]
+   * @param {Function|*} [fn] - custom option processing function or default value
+   * @param {*} [defaultValue]
+   * @return {Command} `this` command for chaining
+   */
+
+  option(flags, description, fn, defaultValue) {
+    return this._optionEx({}, flags, description, fn, defaultValue);
+  }
+
+  /**
+  * Add a required option which must have a value after parsing. This usually means
+  * the option must be specified on the command line. (Otherwise the same as .option().)
+  *
+  * The `flags` string contains the short and/or long flags, separated by comma, a pipe or space.
+  *
+  * @param {string} flags
+  * @param {string} [description]
+  * @param {Function|*} [fn] - custom option processing function or default value
+  * @param {*} [defaultValue]
+  * @return {Command} `this` command for chaining
+  */
+
+  requiredOption(flags, description, fn, defaultValue) {
+    return this._optionEx({ mandatory: true }, flags, description, fn, defaultValue);
+  }
+
+  /**
+   * Alter parsing of short flags with optional values.
+   *
+   * @example
+   * // for `.option('-f,--flag [value]'):
+   * program.combineFlagAndOptionalValue(true);  // `-f80` is treated like `--flag=80`, this is the default behaviour
+   * program.combineFlagAndOptionalValue(false) // `-fb` is treated like `-f -b`
+   *
+   * @param {Boolean} [combine=true] - if `true` or omitted, an optional value can be specified directly after the flag.
+   */
+  combineFlagAndOptionalValue(combine = true) {
+    this._combineFlagAndOptionalValue = !!combine;
+    return this;
+  }
+
+  /**
+   * Allow unknown options on the command line.
+   *
+   * @param {Boolean} [allowUnknown=true] - if `true` or omitted, no error will be thrown
+   * for unknown options.
+   */
+  allowUnknownOption(allowUnknown = true) {
+    this._allowUnknownOption = !!allowUnknown;
+    return this;
+  }
+
+  /**
+   * Allow excess command-arguments on the command line. Pass false to make excess arguments an error.
+   *
+   * @param {Boolean} [allowExcess=true] - if `true` or omitted, no error will be thrown
+   * for excess arguments.
+   */
+  allowExcessArguments(allowExcess = true) {
+    this._allowExcessArguments = !!allowExcess;
+    return this;
+  }
+
+  /**
+   * Enable positional options. Positional means global options are specified before subcommands which lets
+   * subcommands reuse the same option names, and also enables subcommands to turn on passThroughOptions.
+   * The default behaviour is non-positional and global options may appear anywhere on the command line.
+   *
+   * @param {Boolean} [positional=true]
+   */
+  enablePositionalOptions(positional = true) {
+    this._enablePositionalOptions = !!positional;
+    return this;
+  }
+
+  /**
+   * Pass through options that come after command-arguments rather than treat them as command-options,
+   * so actual command-options come before command-arguments. Turning this on for a subcommand requires
+   * positional options to have been enabled on the program (parent commands).
+   * The default behaviour is non-positional and options may appear before or after command-arguments.
+   *
+   * @param {Boolean} [passThrough=true]
+   * for unknown options.
+   */
+  passThroughOptions(passThrough = true) {
+    this._passThroughOptions = !!passThrough;
+    if (!!this.parent && passThrough && !this.parent._enablePositionalOptions) {
+      throw new Error('passThroughOptions can not be used without turning on enablePositionalOptions for parent command(s)');
+    }
+    return this;
+  }
+
+  /**
+    * Whether to store option values as properties on command object,
+    * or store separately (specify false). In both cases the option values can be accessed using .opts().
+    *
+    * @param {boolean} [storeAsProperties=true]
+    * @return {Command} `this` command for chaining
+    */
+
+  storeOptionsAsProperties(storeAsProperties = true) {
+    this._storeOptionsAsProperties = !!storeAsProperties;
+    if (this.options.length) {
+      throw new Error('call .storeOptionsAsProperties() before adding options');
+    }
+    return this;
+  }
+
+  /**
+   * Retrieve option value.
+   *
+   * @param {string} key
+   * @return {Object} value
+   */
+
+  getOptionValue(key) {
+    if (this._storeOptionsAsProperties) {
+      return this[key];
+    }
+    return this._optionValues[key];
+  }
+
+  /**
+   * Store option value.
+   *
+   * @param {string} key
+   * @param {Object} value
+   * @return {Command} `this` command for chaining
+   */
+
+  setOptionValue(key, value) {
+    return this.setOptionValueWithSource(key, value, undefined);
+  }
+
+  /**
+    * Store option value and where the value came from.
+    *
+    * @param {string} key
+    * @param {Object} value
+    * @param {string} source - expected values are default/config/env/cli/implied
+    * @return {Command} `this` command for chaining
+    */
+
+  setOptionValueWithSource(key, value, source) {
+    if (this._storeOptionsAsProperties) {
+      this[key] = value;
+    } else {
+      this._optionValues[key] = value;
+    }
+    this._optionValueSources[key] = source;
+    return this;
+  }
+
+  /**
+    * Get source of option value.
+    * Expected values are default | config | env | cli | implied
+    *
+    * @param {string} key
+    * @return {string}
+    */
+
+  getOptionValueSource(key) {
+    return this._optionValueSources[key];
+  }
+
+  /**
+    * Get source of option value. See also .optsWithGlobals().
+    * Expected values are default | config | env | cli | implied
+    *
+    * @param {string} key
+    * @return {string}
+    */
+
+  getOptionValueSourceWithGlobals(key) {
+    // global overwrites local, like optsWithGlobals
+    let source;
+    getCommandAndParents(this).forEach((cmd) => {
+      if (cmd.getOptionValueSource(key) !== undefined) {
+        source = cmd.getOptionValueSource(key);
+      }
+    });
+    return source;
+  }
+
+  /**
+   * Get user arguments from implied or explicit arguments.
+   * Side-effects: set _scriptPath if args included script. Used for default program name, and subcommand searches.
+   *
+   * @api private
+   */
+
+  _prepareUserArgs(argv, parseOptions) {
+    if (argv !== undefined && !Array.isArray(argv)) {
+      throw new Error('first parameter to parse must be array or undefined');
+    }
+    parseOptions = parseOptions || {};
+
+    // Default to using process.argv
+    if (argv === undefined) {
+      argv = process.argv;
+      // @ts-ignore: unknown property
+      if (process.versions && process.versions.electron) {
+        parseOptions.from = 'electron';
+      }
+    }
+    this.rawArgs = argv.slice();
+
+    // make it a little easier for callers by supporting various argv conventions
+    let userArgs;
+    switch (parseOptions.from) {
+      case undefined:
+      case 'node':
+        this._scriptPath = argv[1];
+        userArgs = argv.slice(2);
+        break;
+      case 'electron':
+        // @ts-ignore: unknown property
+        if (process.defaultApp) {
+          this._scriptPath = argv[1];
+          userArgs = argv.slice(2);
+        } else {
+          userArgs = argv.slice(1);
+        }
+        break;
+      case 'user':
+        userArgs = argv.slice(0);
+        break;
+      default:
+        throw new Error(`unexpected parse option { from: '${parseOptions.from}' }`);
+    }
+
+    // Find default name for program from arguments.
+    if (!this._name && this._scriptPath) this.nameFromFilename(this._scriptPath);
+    this._name = this._name || 'program';
+
+    return userArgs;
+  }
+
+  /**
+   * Parse `argv`, setting options and invoking commands when defined.
+   *
+   * The default expectation is that the arguments are from node and have the application as argv[0]
+   * and the script being run in argv[1], with user parameters after that.
+   *
+   * @example
+   * program.parse(process.argv);
+   * program.parse(); // implicitly use process.argv and auto-detect node vs electron conventions
+   * program.parse(my-args, { from: 'user' }); // just user supplied arguments, nothing special about argv[0]
+   *
+   * @param {string[]} [argv] - optional, defaults to process.argv
+   * @param {Object} [parseOptions] - optionally specify style of options with from: node/user/electron
+   * @param {string} [parseOptions.from] - where the args are from: 'node', 'user', 'electron'
+   * @return {Command} `this` command for chaining
+   */
+
+  parse(argv, parseOptions) {
+    const userArgs = this._prepareUserArgs(argv, parseOptions);
+    this._parseCommand([], userArgs);
+
+    return this;
+  }
+
+  /**
+   * Parse `argv`, setting options and invoking commands when defined.
+   *
+   * Use parseAsync instead of parse if any of your action handlers are async. Returns a Promise.
+   *
+   * The default expectation is that the arguments are from node and have the application as argv[0]
+   * and the script being run in argv[1], with user parameters after that.
+   *
+   * @example
+   * await program.parseAsync(process.argv);
+   * await program.parseAsync(); // implicitly use process.argv and auto-detect node vs electron conventions
+   * await program.parseAsync(my-args, { from: 'user' }); // just user supplied arguments, nothing special about argv[0]
+   *
+   * @param {string[]} [argv]
+   * @param {Object} [parseOptions]
+   * @param {string} parseOptions.from - where the args are from: 'node', 'user', 'electron'
+   * @return {Promise}
+   */
+
+  async parseAsync(argv, parseOptions) {
+    const userArgs = this._prepareUserArgs(argv, parseOptions);
+    await this._parseCommand([], userArgs);
+
+    return this;
+  }
+
+  /**
+   * Execute a sub-command executable.
+   *
+   * @api private
+   */
+
+  _executeSubCommand(subcommand, args) {
+    args = args.slice();
+    let launchWithNode = false; // Use node for source targets so do not need to get permissions correct, and on Windows.
+    const sourceExt = ['.js', '.ts', '.tsx', '.mjs', '.cjs'];
+
+    function findFile(baseDir, baseName) {
+      // Look for specified file
+      const localBin = path.resolve(baseDir, baseName);
+      if (fs.existsSync(localBin)) return localBin;
+
+      // Stop looking if candidate already has an expected extension.
+      if (sourceExt.includes(path.extname(baseName))) return undefined;
+
+      // Try all the extensions.
+      const foundExt = sourceExt.find(ext => fs.existsSync(`${localBin}${ext}`));
+      if (foundExt) return `${localBin}${foundExt}`;
+
+      return undefined;
+    }
+
+    // Not checking for help first. Unlikely to have mandatory and executable, and can't robustly test for help flags in external command.
+    this._checkForMissingMandatoryOptions();
+    this._checkForConflictingOptions();
+
+    // executableFile and executableDir might be full path, or just a name
+    let executableFile = subcommand._executableFile || `${this._name}-${subcommand._name}`;
+    let executableDir = this._executableDir || '';
+    if (this._scriptPath) {
+      let resolvedScriptPath; // resolve possible symlink for installed npm binary
+      try {
+        resolvedScriptPath = fs.realpathSync(this._scriptPath);
+      } catch (err) {
+        resolvedScriptPath = this._scriptPath;
+      }
+      executableDir = path.resolve(path.dirname(resolvedScriptPath), executableDir);
+    }
+
+    // Look for a local file in preference to a command in PATH.
+    if (executableDir) {
+      let localFile = findFile(executableDir, executableFile);
+
+      // Legacy search using prefix of script name instead of command name
+      if (!localFile && !subcommand._executableFile && this._scriptPath) {
+        const legacyName = path.basename(this._scriptPath, path.extname(this._scriptPath));
+        if (legacyName !== this._name) {
+          localFile = findFile(executableDir, `${legacyName}-${subcommand._name}`);
+        }
+      }
+      executableFile = localFile || executableFile;
+    }
+
+    launchWithNode = sourceExt.includes(path.extname(executableFile));
+
+    let proc;
+    if (process.platform !== 'win32') {
+      if (launchWithNode) {
+        args.unshift(executableFile);
+        // add executable arguments to spawn
+        args = incrementNodeInspectorPort(process.execArgv).concat(args);
+
+        proc = childProcess.spawn(process.argv[0], args, { stdio: 'inherit' });
+      } else {
+        proc = childProcess.spawn(executableFile, args, { stdio: 'inherit' });
+      }
+    } else {
+      args.unshift(executableFile);
+      // add executable arguments to spawn
+      args = incrementNodeInspectorPort(process.execArgv).concat(args);
+      proc = childProcess.spawn(process.execPath, args, { stdio: 'inherit' });
+    }
+
+    if (!proc.killed) { // testing mainly to avoid leak warnings during unit tests with mocked spawn
+      const signals = ['SIGUSR1', 'SIGUSR2', 'SIGTERM', 'SIGINT', 'SIGHUP'];
+      signals.forEach((signal) => {
+        // @ts-ignore
+        process.on(signal, () => {
+          if (proc.killed === false && proc.exitCode === null) {
+            proc.kill(signal);
+          }
+        });
+      });
+    }
+
+    // By default terminate process when spawned process terminates.
+    // Suppressing the exit if exitCallback defined is a bit messy and of limited use, but does allow process to stay running!
+    const exitCallback = this._exitCallback;
+    if (!exitCallback) {
+      proc.on('close', process.exit.bind(process));
+    } else {
+      proc.on('close', () => {
+        exitCallback(new CommanderError(process.exitCode || 0, 'commander.executeSubCommandAsync', '(close)'));
+      });
+    }
+    proc.on('error', (err) => {
+      // @ts-ignore
+      if (err.code === 'ENOENT') {
+        const executableDirMessage = executableDir
+          ? `searched for local subcommand relative to directory '${executableDir}'`
+          : 'no directory for search for local subcommand, use .executableDir() to supply a custom directory';
+        const executableMissing = `'${executableFile}' does not exist
+ - if '${subcommand._name}' is not meant to be an executable command, remove description parameter from '.command()' and use '.description()' instead
+ - if the default executable name is not suitable, use the executableFile option to supply a custom name or path
+ - ${executableDirMessage}`;
+        throw new Error(executableMissing);
+      // @ts-ignore
+      } else if (err.code === 'EACCES') {
+        throw new Error(`'${executableFile}' not executable`);
+      }
+      if (!exitCallback) {
+        process.exit(1);
+      } else {
+        const wrappedError = new CommanderError(1, 'commander.executeSubCommandAsync', '(error)');
+        wrappedError.nestedError = err;
+        exitCallback(wrappedError);
+      }
+    });
+
+    // Store the reference to the child process
+    this.runningCommand = proc;
+  }
+
+  /**
+   * @api private
+   */
+
+  _dispatchSubcommand(commandName, operands, unknown) {
+    const subCommand = this._findCommand(commandName);
+    if (!subCommand) this.help({ error: true });
+
+    let hookResult;
+    hookResult = this._chainOrCallSubCommandHook(hookResult, subCommand, 'preSubcommand');
+    hookResult = this._chainOrCall(hookResult, () => {
+      if (subCommand._executableHandler) {
+        this._executeSubCommand(subCommand, operands.concat(unknown));
+      } else {
+        return subCommand._parseCommand(operands, unknown);
+      }
+    });
+    return hookResult;
+  }
+
+  /**
+   * Check this.args against expected this._args.
+   *
+   * @api private
+   */
+
+  _checkNumberOfArguments() {
+    // too few
+    this._args.forEach((arg, i) => {
+      if (arg.required && this.args[i] == null) {
+        this.missingArgument(arg.name());
+      }
+    });
+    // too many
+    if (this._args.length > 0 && this._args[this._args.length - 1].variadic) {
+      return;
+    }
+    if (this.args.length > this._args.length) {
+      this._excessArguments(this.args);
+    }
+  }
+
+  /**
+   * Process this.args using this._args and save as this.processedArgs!
+   *
+   * @api private
+   */
+
+  _processArguments() {
+    const myParseArg = (argument, value, previous) => {
+      // Extra processing for nice error message on parsing failure.
+      let parsedValue = value;
+      if (value !== null && argument.parseArg) {
+        try {
+          parsedValue = argument.parseArg(value, previous);
+        } catch (err) {
+          if (err.code === 'commander.invalidArgument') {
+            const message = `error: command-argument value '${value}' is invalid for argument '${argument.name()}'. ${err.message}`;
+            this.error(message, { exitCode: err.exitCode, code: err.code });
+          }
+          throw err;
+        }
+      }
+      return parsedValue;
+    };
+
+    this._checkNumberOfArguments();
+
+    const processedArgs = [];
+    this._args.forEach((declaredArg, index) => {
+      let value = declaredArg.defaultValue;
+      if (declaredArg.variadic) {
+        // Collect together remaining arguments for passing together as an array.
+        if (index < this.args.length) {
+          value = this.args.slice(index);
+          if (declaredArg.parseArg) {
+            value = value.reduce((processed, v) => {
+              return myParseArg(declaredArg, v, processed);
+            }, declaredArg.defaultValue);
+          }
+        } else if (value === undefined) {
+          value = [];
+        }
+      } else if (index < this.args.length) {
+        value = this.args[index];
+        if (declaredArg.parseArg) {
+          value = myParseArg(declaredArg, value, declaredArg.defaultValue);
+        }
+      }
+      processedArgs[index] = value;
+    });
+    this.processedArgs = processedArgs;
+  }
+
+  /**
+   * Once we have a promise we chain, but call synchronously until then.
+   *
+   * @param {Promise|undefined} promise
+   * @param {Function} fn
+   * @return {Promise|undefined}
+   * @api private
+   */
+
+  _chainOrCall(promise, fn) {
+    // thenable
+    if (promise && promise.then && typeof promise.then === 'function') {
+      // already have a promise, chain callback
+      return promise.then(() => fn());
+    }
+    // callback might return a promise
+    return fn();
+  }
+
+  /**
+   *
+   * @param {Promise|undefined} promise
+   * @param {string} event
+   * @return {Promise|undefined}
+   * @api private
+   */
+
+  _chainOrCallHooks(promise, event) {
+    let result = promise;
+    const hooks = [];
+    getCommandAndParents(this)
+      .reverse()
+      .filter(cmd => cmd._lifeCycleHooks[event] !== undefined)
+      .forEach(hookedCommand => {
+        hookedCommand._lifeCycleHooks[event].forEach((callback) => {
+          hooks.push({ hookedCommand, callback });
+        });
+      });
+    if (event === 'postAction') {
+      hooks.reverse();
+    }
+
+    hooks.forEach((hookDetail) => {
+      result = this._chainOrCall(result, () => {
+        return hookDetail.callback(hookDetail.hookedCommand, this);
+      });
+    });
+    return result;
+  }
+
+  /**
+   *
+   * @param {Promise|undefined} promise
+   * @param {Command} subCommand
+   * @param {string} event
+   * @return {Promise|undefined}
+   * @api private
+   */
+
+  _chainOrCallSubCommandHook(promise, subCommand, event) {
+    let result = promise;
+    if (this._lifeCycleHooks[event] !== undefined) {
+      this._lifeCycleHooks[event].forEach((hook) => {
+        result = this._chainOrCall(result, () => {
+          return hook(this, subCommand);
+        });
+      });
+    }
+    return result;
+  }
+
+  /**
+   * Process arguments in context of this command.
+   * Returns action result, in case it is a promise.
+   *
+   * @api private
+   */
+
+  _parseCommand(operands, unknown) {
+    const parsed = this.parseOptions(unknown);
+    this._parseOptionsEnv(); // after cli, so parseArg not called on both cli and env
+    this._parseOptionsImplied();
+    operands = operands.concat(parsed.operands);
+    unknown = parsed.unknown;
+    this.args = operands.concat(unknown);
+
+    if (operands && this._findCommand(operands[0])) {
+      return this._dispatchSubcommand(operands[0], operands.slice(1), unknown);
+    }
+    if (this._hasImplicitHelpCommand() && operands[0] === this._helpCommandName) {
+      if (operands.length === 1) {
+        this.help();
+      }
+      return this._dispatchSubcommand(operands[1], [], [this._helpLongFlag]);
+    }
+    if (this._defaultCommandName) {
+      outputHelpIfRequested(this, unknown); // Run the help for default command from parent rather than passing to default command
+      return this._dispatchSubcommand(this._defaultCommandName, operands, unknown);
+    }
+    if (this.commands.length && this.args.length === 0 && !this._actionHandler && !this._defaultCommandName) {
+      // probably missing subcommand and no handler, user needs help (and exit)
+      this.help({ error: true });
+    }
+
+    outputHelpIfRequested(this, parsed.unknown);
+    this._checkForMissingMandatoryOptions();
+    this._checkForConflictingOptions();
+
+    // We do not always call this check to avoid masking a "better" error, like unknown command.
+    const checkForUnknownOptions = () => {
+      if (parsed.unknown.length > 0) {
+        this.unknownOption(parsed.unknown[0]);
+      }
+    };
+
+    const commandEvent = `command:${this.name()}`;
+    if (this._actionHandler) {
+      checkForUnknownOptions();
+      this._processArguments();
+
+      let actionResult;
+      actionResult = this._chainOrCallHooks(actionResult, 'preAction');
+      actionResult = this._chainOrCall(actionResult, () => this._actionHandler(this.processedArgs));
+      if (this.parent) {
+        actionResult = this._chainOrCall(actionResult, () => {
+          this.parent.emit(commandEvent, operands, unknown); // legacy
+        });
+      }
+      actionResult = this._chainOrCallHooks(actionResult, 'postAction');
+      return actionResult;
+    }
+    if (this.parent && this.parent.listenerCount(commandEvent)) {
+      checkForUnknownOptions();
+      this._processArguments();
+      this.parent.emit(commandEvent, operands, unknown); // legacy
+    } else if (operands.length) {
+      if (this._findCommand('*')) { // legacy default command
+        return this._dispatchSubcommand('*', operands, unknown);
+      }
+      if (this.listenerCount('command:*')) {
+        // skip option check, emit event for possible misspelling suggestion
+        this.emit('command:*', operands, unknown);
+      } else if (this.commands.length) {
+        this.unknownCommand();
+      } else {
+        checkForUnknownOptions();
+        this._processArguments();
+      }
+    } else if (this.commands.length) {
+      checkForUnknownOptions();
+      // This command has subcommands and nothing hooked up at this level, so display help (and exit).
+      this.help({ error: true });
+    } else {
+      checkForUnknownOptions();
+      this._processArguments();
+      // fall through for caller to handle after calling .parse()
+    }
+  }
+
+  /**
+   * Find matching command.
+   *
+   * @api private
+   */
+  _findCommand(name) {
+    if (!name) return undefined;
+    return this.commands.find(cmd => cmd._name === name || cmd._aliases.includes(name));
+  }
+
+  /**
+   * Return an option matching `arg` if any.
+   *
+   * @param {string} arg
+   * @return {Option}
+   * @api private
+   */
+
+  _findOption(arg) {
+    return this.options.find(option => option.is(arg));
+  }
+
+  /**
+   * Display an error message if a mandatory option does not have a value.
+   * Called after checking for help flags in leaf subcommand.
+   *
+   * @api private
+   */
+
+  _checkForMissingMandatoryOptions() {
+    // Walk up hierarchy so can call in subcommand after checking for displaying help.
+    for (let cmd = this; cmd; cmd = cmd.parent) {
+      cmd.options.forEach((anOption) => {
+        if (anOption.mandatory && (cmd.getOptionValue(anOption.attributeName()) === undefined)) {
+          cmd.missingMandatoryOptionValue(anOption);
+        }
+      });
+    }
+  }
+
+  /**
+   * Display an error message if conflicting options are used together in this.
+   *
+   * @api private
+   */
+  _checkForConflictingLocalOptions() {
+    const definedNonDefaultOptions = this.options.filter(
+      (option) => {
+        const optionKey = option.attributeName();
+        if (this.getOptionValue(optionKey) === undefined) {
+          return false;
+        }
+        return this.getOptionValueSource(optionKey) !== 'default';
+      }
+    );
+
+    const optionsWithConflicting = definedNonDefaultOptions.filter(
+      (option) => option.conflictsWith.length > 0
+    );
+
+    optionsWithConflicting.forEach((option) => {
+      const conflictingAndDefined = definedNonDefaultOptions.find((defined) =>
+        option.conflictsWith.includes(defined.attributeName())
+      );
+      if (conflictingAndDefined) {
+        this._conflictingOption(option, conflictingAndDefined);
+      }
+    });
+  }
+
+  /**
+   * Display an error message if conflicting options are used together.
+   * Called after checking for help flags in leaf subcommand.
+   *
+   * @api private
+   */
+  _checkForConflictingOptions() {
+    // Walk up hierarchy so can call in subcommand after checking for displaying help.
+    for (let cmd = this; cmd; cmd = cmd.parent) {
+      cmd._checkForConflictingLocalOptions();
+    }
+  }
+
+  /**
+   * Parse options from `argv` removing known options,
+   * and return argv split into operands and unknown arguments.
+   *
+   * Examples:
+   *
+   *     argv => operands, unknown
+   *     --known kkk op => [op], []
+   *     op --known kkk => [op], []
+   *     sub --unknown uuu op => [sub], [--unknown uuu op]
+   *     sub -- --unknown uuu op => [sub --unknown uuu op], []
+   *
+   * @param {String[]} argv
+   * @return {{operands: String[], unknown: String[]}}
+   */
+
+  parseOptions(argv) {
+    const operands = []; // operands, not options or values
+    const unknown = []; // first unknown option and remaining unknown args
+    let dest = operands;
+    const args = argv.slice();
+
+    function maybeOption(arg) {
+      return arg.length > 1 && arg[0] === '-';
+    }
+
+    // parse options
+    let activeVariadicOption = null;
+    while (args.length) {
+      const arg = args.shift();
+
+      // literal
+      if (arg === '--') {
+        if (dest === unknown) dest.push(arg);
+        dest.push(...args);
+        break;
+      }
+
+      if (activeVariadicOption && !maybeOption(arg)) {
+        this.emit(`option:${activeVariadicOption.name()}`, arg);
+        continue;
+      }
+      activeVariadicOption = null;
+
+      if (maybeOption(arg)) {
+        const option = this._findOption(arg);
+        // recognised option, call listener to assign value with possible custom processing
+        if (option) {
+          if (option.required) {
+            const value = args.shift();
+            if (value === undefined) this.optionMissingArgument(option);
+            this.emit(`option:${option.name()}`, value);
+          } else if (option.optional) {
+            let value = null;
+            // historical behaviour is optional value is following arg unless an option
+            if (args.length > 0 && !maybeOption(args[0])) {
+              value = args.shift();
+            }
+            this.emit(`option:${option.name()}`, value);
+          } else { // boolean flag
+            this.emit(`option:${option.name()}`);
+          }
+          activeVariadicOption = option.variadic ? option : null;
+          continue;
+        }
+      }
+
+      // Look for combo options following single dash, eat first one if known.
+      if (arg.length > 2 && arg[0] === '-' && arg[1] !== '-') {
+        const option = this._findOption(`-${arg[1]}`);
+        if (option) {
+          if (option.required || (option.optional && this._combineFlagAndOptionalValue)) {
+            // option with value following in same argument
+            this.emit(`option:${option.name()}`, arg.slice(2));
+          } else {
+            // boolean option, emit and put back remainder of arg for further processing
+            this.emit(`option:${option.name()}`);
+            args.unshift(`-${arg.slice(2)}`);
+          }
+          continue;
+        }
+      }
+
+      // Look for known long flag with value, like --foo=bar
+      if (/^--[^=]+=/.test(arg)) {
+        const index = arg.indexOf('=');
+        const option = this._findOption(arg.slice(0, index));
+        if (option && (option.required || option.optional)) {
+          this.emit(`option:${option.name()}`, arg.slice(index + 1));
+          continue;
+        }
+      }
+
+      // Not a recognised option by this command.
+      // Might be a command-argument, or subcommand option, or unknown option, or help command or option.
+
+      // An unknown option means further arguments also classified as unknown so can be reprocessed by subcommands.
+      if (maybeOption(arg)) {
+        dest = unknown;
+      }
+
+      // If using positionalOptions, stop processing our options at subcommand.
+      if ((this._enablePositionalOptions || this._passThroughOptions) && operands.length === 0 && unknown.length === 0) {
+        if (this._findCommand(arg)) {
+          operands.push(arg);
+          if (args.length > 0) unknown.push(...args);
+          break;
+        } else if (arg === this._helpCommandName && this._hasImplicitHelpCommand()) {
+          operands.push(arg);
+          if (args.length > 0) operands.push(...args);
+          break;
+        } else if (this._defaultCommandName) {
+          unknown.push(arg);
+          if (args.length > 0) unknown.push(...args);
+          break;
+        }
+      }
+
+      // If using passThroughOptions, stop processing options at first command-argument.
+      if (this._passThroughOptions) {
+        dest.push(arg);
+        if (args.length > 0) dest.push(...args);
+        break;
+      }
+
+      // add arg
+      dest.push(arg);
+    }
+
+    return { operands, unknown };
+  }
+
+  /**
+   * Return an object containing local option values as key-value pairs.
+   *
+   * @return {Object}
+   */
+  opts() {
+    if (this._storeOptionsAsProperties) {
+      // Preserve original behaviour so backwards compatible when still using properties
+      const result = {};
+      const len = this.options.length;
+
+      for (let i = 0; i < len; i++) {
+        const key = this.options[i].attributeName();
+        result[key] = key === this._versionOptionName ? this._version : this[key];
+      }
+      return result;
+    }
+
+    return this._optionValues;
+  }
+
+  /**
+   * Return an object containing merged local and global option values as key-value pairs.
+   *
+   * @return {Object}
+   */
+  optsWithGlobals() {
+    // globals overwrite locals
+    return getCommandAndParents(this).reduce(
+      (combinedOptions, cmd) => Object.assign(combinedOptions, cmd.opts()),
+      {}
+    );
+  }
+
+  /**
+   * Display error message and exit (or call exitOverride).
+   *
+   * @param {string} message
+   * @param {Object} [errorOptions]
+   * @param {string} [errorOptions.code] - an id string representing the error
+   * @param {number} [errorOptions.exitCode] - used with process.exit
+   */
+  error(message, errorOptions) {
+    // output handling
+    this._outputConfiguration.outputError(`${message}\n`, this._outputConfiguration.writeErr);
+    if (typeof this._showHelpAfterError === 'string') {
+      this._outputConfiguration.writeErr(`${this._showHelpAfterError}\n`);
+    } else if (this._showHelpAfterError) {
+      this._outputConfiguration.writeErr('\n');
+      this.outputHelp({ error: true });
+    }
+
+    // exit handling
+    const config = errorOptions || {};
+    const exitCode = config.exitCode || 1;
+    const code = config.code || 'commander.error';
+    this._exit(exitCode, code, message);
+  }
+
+  /**
+   * Apply any option related environment variables, if option does
+   * not have a value from cli or client code.
+   *
+   * @api private
+   */
+  _parseOptionsEnv() {
+    this.options.forEach((option) => {
+      if (option.envVar && option.envVar in process.env) {
+        const optionKey = option.attributeName();
+        // Priority check. Do not overwrite cli or options from unknown source (client-code).
+        if (this.getOptionValue(optionKey) === undefined || ['default', 'config', 'env'].includes(this.getOptionValueSource(optionKey))) {
+          if (option.required || option.optional) { // option can take a value
+            // keep very simple, optional always takes value
+            this.emit(`optionEnv:${option.name()}`, process.env[option.envVar]);
+          } else { // boolean
+            // keep very simple, only care that envVar defined and not the value
+            this.emit(`optionEnv:${option.name()}`);
+          }
+        }
+      }
+    });
+  }
+
+  /**
+   * Apply any implied option values, if option is undefined or default value.
+   *
+   * @api private
+   */
+  _parseOptionsImplied() {
+    const dualHelper = new DualOptions(this.options);
+    const hasCustomOptionValue = (optionKey) => {
+      return this.getOptionValue(optionKey) !== undefined && !['default', 'implied'].includes(this.getOptionValueSource(optionKey));
+    };
+    this.options
+      .filter(option => (option.implied !== undefined) &&
+        hasCustomOptionValue(option.attributeName()) &&
+        dualHelper.valueFromOption(this.getOptionValue(option.attributeName()), option))
+      .forEach((option) => {
+        Object.keys(option.implied)
+          .filter(impliedKey => !hasCustomOptionValue(impliedKey))
+          .forEach(impliedKey => {
+            this.setOptionValueWithSource(impliedKey, option.implied[impliedKey], 'implied');
+          });
+      });
+  }
+
+  /**
+   * Argument `name` is missing.
+   *
+   * @param {string} name
+   * @api private
+   */
+
+  missingArgument(name) {
+    const message = `error: missing required argument '${name}'`;
+    this.error(message, { code: 'commander.missingArgument' });
+  }
+
+  /**
+   * `Option` is missing an argument.
+   *
+   * @param {Option} option
+   * @api private
+   */
+
+  optionMissingArgument(option) {
+    const message = `error: option '${option.flags}' argument missing`;
+    this.error(message, { code: 'commander.optionMissingArgument' });
+  }
+
+  /**
+   * `Option` does not have a value, and is a mandatory option.
+   *
+   * @param {Option} option
+   * @api private
+   */
+
+  missingMandatoryOptionValue(option) {
+    const message = `error: required option '${option.flags}' not specified`;
+    this.error(message, { code: 'commander.missingMandatoryOptionValue' });
+  }
+
+  /**
+   * `Option` conflicts with another option.
+   *
+   * @param {Option} option
+   * @param {Option} conflictingOption
+   * @api private
+   */
+  _conflictingOption(option, conflictingOption) {
+    // The calling code does not know whether a negated option is the source of the
+    // value, so do some work to take an educated guess.
+    const findBestOptionFromValue = (option) => {
+      const optionKey = option.attributeName();
+      const optionValue = this.getOptionValue(optionKey);
+      const negativeOption = this.options.find(target => target.negate && optionKey === target.attributeName());
+      const positiveOption = this.options.find(target => !target.negate && optionKey === target.attributeName());
+      if (negativeOption && (
+        (negativeOption.presetArg === undefined && optionValue === false) ||
+        (negativeOption.presetArg !== undefined && optionValue === negativeOption.presetArg)
+      )) {
+        return negativeOption;
+      }
+      return positiveOption || option;
+    };
+
+    const getErrorMessage = (option) => {
+      const bestOption = findBestOptionFromValue(option);
+      const optionKey = bestOption.attributeName();
+      const source = this.getOptionValueSource(optionKey);
+      if (source === 'env') {
+        return `environment variable '${bestOption.envVar}'`;
+      }
+      return `option '${bestOption.flags}'`;
+    };
+
+    const message = `error: ${getErrorMessage(option)} cannot be used with ${getErrorMessage(conflictingOption)}`;
+    this.error(message, { code: 'commander.conflictingOption' });
+  }
+
+  /**
+   * Unknown option `flag`.
+   *
+   * @param {string} flag
+   * @api private
+   */
+
+  unknownOption(flag) {
+    if (this._allowUnknownOption) return;
+    let suggestion = '';
+
+    if (flag.startsWith('--') && this._showSuggestionAfterError) {
+      // Looping to pick up the global options too
+      let candidateFlags = [];
+      let command = this;
+      do {
+        const moreFlags = command.createHelp().visibleOptions(command)
+          .filter(option => option.long)
+          .map(option => option.long);
+        candidateFlags = candidateFlags.concat(moreFlags);
+        command = command.parent;
+      } while (command && !command._enablePositionalOptions);
+      suggestion = suggestSimilar(flag, candidateFlags);
+    }
+
+    const message = `error: unknown option '${flag}'${suggestion}`;
+    this.error(message, { code: 'commander.unknownOption' });
+  }
+
+  /**
+   * Excess arguments, more than expected.
+   *
+   * @param {string[]} receivedArgs
+   * @api private
+   */
+
+  _excessArguments(receivedArgs) {
+    if (this._allowExcessArguments) return;
+
+    const expected = this._args.length;
+    const s = (expected === 1) ? '' : 's';
+    const forSubcommand = this.parent ? ` for '${this.name()}'` : '';
+    const message = `error: too many arguments${forSubcommand}. Expected ${expected} argument${s} but got ${receivedArgs.length}.`;
+    this.error(message, { code: 'commander.excessArguments' });
+  }
+
+  /**
+   * Unknown command.
+   *
+   * @api private
+   */
+
+  unknownCommand() {
+    const unknownName = this.args[0];
+    let suggestion = '';
+
+    if (this._showSuggestionAfterError) {
+      const candidateNames = [];
+      this.createHelp().visibleCommands(this).forEach((command) => {
+        candidateNames.push(command.name());
+        // just visible alias
+        if (command.alias()) candidateNames.push(command.alias());
+      });
+      suggestion = suggestSimilar(unknownName, candidateNames);
+    }
+
+    const message = `error: unknown command '${unknownName}'${suggestion}`;
+    this.error(message, { code: 'commander.unknownCommand' });
+  }
+
+  /**
+   * Set the program version to `str`.
+   *
+   * This method auto-registers the "-V, --version" flag
+   * which will print the version number when passed.
+   *
+   * You can optionally supply the  flags and description to override the defaults.
+   *
+   * @param {string} str
+   * @param {string} [flags]
+   * @param {string} [description]
+   * @return {this | string} `this` command for chaining, or version string if no arguments
+   */
+
+  version(str, flags, description) {
+    if (str === undefined) return this._version;
+    this._version = str;
+    flags = flags || '-V, --version';
+    description = description || 'output the version number';
+    const versionOption = this.createOption(flags, description);
+    this._versionOptionName = versionOption.attributeName();
+    this.options.push(versionOption);
+    this.on('option:' + versionOption.name(), () => {
+      this._outputConfiguration.writeOut(`${str}\n`);
+      this._exit(0, 'commander.version', str);
+    });
+    return this;
+  }
+
+  /**
+   * Set the description.
+   *
+   * @param {string} [str]
+   * @param {Object} [argsDescription]
+   * @return {string|Command}
+   */
+  description(str, argsDescription) {
+    if (str === undefined && argsDescription === undefined) return this._description;
+    this._description = str;
+    if (argsDescription) {
+      this._argsDescription = argsDescription;
+    }
+    return this;
+  }
+
+  /**
+   * Set the summary. Used when listed as subcommand of parent.
+   *
+   * @param {string} [str]
+   * @return {string|Command}
+   */
+  summary(str) {
+    if (str === undefined) return this._summary;
+    this._summary = str;
+    return this;
+  }
+
+  /**
+   * Set an alias for the command.
+   *
+   * You may call more than once to add multiple aliases. Only the first alias is shown in the auto-generated help.
+   *
+   * @param {string} [alias]
+   * @return {string|Command}
+   */
+
+  alias(alias) {
+    if (alias === undefined) return this._aliases[0]; // just return first, for backwards compatibility
+
+    /** @type {Command} */
+    let command = this;
+    if (this.commands.length !== 0 && this.commands[this.commands.length - 1]._executableHandler) {
+      // assume adding alias for last added executable subcommand, rather than this
+      command = this.commands[this.commands.length - 1];
+    }
+
+    if (alias === command._name) throw new Error('Command alias can\'t be the same as its name');
+
+    command._aliases.push(alias);
+    return this;
+  }
+
+  /**
+   * Set aliases for the command.
+   *
+   * Only the first alias is shown in the auto-generated help.
+   *
+   * @param {string[]} [aliases]
+   * @return {string[]|Command}
+   */
+
+  aliases(aliases) {
+    // Getter for the array of aliases is the main reason for having aliases() in addition to alias().
+    if (aliases === undefined) return this._aliases;
+
+    aliases.forEach((alias) => this.alias(alias));
+    return this;
+  }
+
+  /**
+   * Set / get the command usage `str`.
+   *
+   * @param {string} [str]
+   * @return {String|Command}
+   */
+
+  usage(str) {
+    if (str === undefined) {
+      if (this._usage) return this._usage;
+
+      const args = this._args.map((arg) => {
+        return humanReadableArgName(arg);
+      });
+      return [].concat(
+        (this.options.length || this._hasHelpOption ? '[options]' : []),
+        (this.commands.length ? '[command]' : []),
+        (this._args.length ? args : [])
+      ).join(' ');
+    }
+
+    this._usage = str;
+    return this;
+  }
+
+  /**
+   * Get or set the name of the command.
+   *
+   * @param {string} [str]
+   * @return {string|Command}
+   */
+
+  name(str) {
+    if (str === undefined) return this._name;
+    this._name = str;
+    return this;
+  }
+
+  /**
+   * Set the name of the command from script filename, such as process.argv[1],
+   * or require.main.filename, or __filename.
+   *
+   * (Used internally and public although not documented in README.)
+   *
+   * @example
+   * program.nameFromFilename(require.main.filename);
+   *
+   * @param {string} filename
+   * @return {Command}
+   */
+
+  nameFromFilename(filename) {
+    this._name = path.basename(filename, path.extname(filename));
+
+    return this;
+  }
+
+  /**
+   * Get or set the directory for searching for executable subcommands of this command.
+   *
+   * @example
+   * program.executableDir(__dirname);
+   * // or
+   * program.executableDir('subcommands');
+   *
+   * @param {string} [path]
+   * @return {string|Command}
+   */
+
+  executableDir(path) {
+    if (path === undefined) return this._executableDir;
+    this._executableDir = path;
+    return this;
+  }
+
+  /**
+   * Return program help documentation.
+   *
+   * @param {{ error: boolean }} [contextOptions] - pass {error:true} to wrap for stderr instead of stdout
+   * @return {string}
+   */
+
+  helpInformation(contextOptions) {
+    const helper = this.createHelp();
+    if (helper.helpWidth === undefined) {
+      helper.helpWidth = (contextOptions && contextOptions.error) ? this._outputConfiguration.getErrHelpWidth() : this._outputConfiguration.getOutHelpWidth();
+    }
+    return helper.formatHelp(this, helper);
+  }
+
+  /**
+   * @api private
+   */
+
+  _getHelpContext(contextOptions) {
+    contextOptions = contextOptions || {};
+    const context = { error: !!contextOptions.error };
+    let write;
+    if (context.error) {
+      write = (arg) => this._outputConfiguration.writeErr(arg);
+    } else {
+      write = (arg) => this._outputConfiguration.writeOut(arg);
+    }
+    context.write = contextOptions.write || write;
+    context.command = this;
+    return context;
+  }
+
+  /**
+   * Output help information for this command.
+   *
+   * Outputs built-in help, and custom text added using `.addHelpText()`.
+   *
+   * @param {{ error: boolean } | Function} [contextOptions] - pass {error:true} to write to stderr instead of stdout
+   */
+
+  outputHelp(contextOptions) {
+    let deprecatedCallback;
+    if (typeof contextOptions === 'function') {
+      deprecatedCallback = contextOptions;
+      contextOptions = undefined;
+    }
+    const context = this._getHelpContext(contextOptions);
+
+    getCommandAndParents(this).reverse().forEach(command => command.emit('beforeAllHelp', context));
+    this.emit('beforeHelp', context);
+
+    let helpInformation = this.helpInformation(context);
+    if (deprecatedCallback) {
+      helpInformation = deprecatedCallback(helpInformation);
+      if (typeof helpInformation !== 'string' && !Buffer.isBuffer(helpInformation)) {
+        throw new Error('outputHelp callback must return a string or a Buffer');
+      }
+    }
+    context.write(helpInformation);
+
+    this.emit(this._helpLongFlag); // deprecated
+    this.emit('afterHelp', context);
+    getCommandAndParents(this).forEach(command => command.emit('afterAllHelp', context));
+  }
+
+  /**
+   * You can pass in flags and a description to override the help
+   * flags and help description for your command. Pass in false to
+   * disable the built-in help option.
+   *
+   * @param {string | boolean} [flags]
+   * @param {string} [description]
+   * @return {Command} `this` command for chaining
+   */
+
+  helpOption(flags, description) {
+    if (typeof flags === 'boolean') {
+      this._hasHelpOption = flags;
+      return this;
+    }
+    this._helpFlags = flags || this._helpFlags;
+    this._helpDescription = description || this._helpDescription;
+
+    const helpFlags = splitOptionFlags(this._helpFlags);
+    this._helpShortFlag = helpFlags.shortFlag;
+    this._helpLongFlag = helpFlags.longFlag;
+
+    return this;
+  }
+
+  /**
+   * Output help information and exit.
+   *
+   * Outputs built-in help, and custom text added using `.addHelpText()`.
+   *
+   * @param {{ error: boolean }} [contextOptions] - pass {error:true} to write to stderr instead of stdout
+   */
+
+  help(contextOptions) {
+    this.outputHelp(contextOptions);
+    let exitCode = process.exitCode || 0;
+    if (exitCode === 0 && contextOptions && typeof contextOptions !== 'function' && contextOptions.error) {
+      exitCode = 1;
+    }
+    // message: do not have all displayed text available so only passing placeholder.
+    this._exit(exitCode, 'commander.help', '(outputHelp)');
+  }
+
+  /**
+   * Add additional text to be displayed with the built-in help.
+   *
+   * Position is 'before' or 'after' to affect just this command,
+   * and 'beforeAll' or 'afterAll' to affect this command and all its subcommands.
+   *
+   * @param {string} position - before or after built-in help
+   * @param {string | Function} text - string to add, or a function returning a string
+   * @return {Command} `this` command for chaining
+   */
+  addHelpText(position, text) {
+    const allowedValues = ['beforeAll', 'before', 'after', 'afterAll'];
+    if (!allowedValues.includes(position)) {
+      throw new Error(`Unexpected value for position to addHelpText.
+Expecting one of '${allowedValues.join("', '")}'`);
+    }
+    const helpEvent = `${position}Help`;
+    this.on(helpEvent, (context) => {
+      let helpStr;
+      if (typeof text === 'function') {
+        helpStr = text({ error: context.error, command: context.command });
+      } else {
+        helpStr = text;
+      }
+      // Ignore falsy value when nothing to output.
+      if (helpStr) {
+        context.write(`${helpStr}\n`);
+      }
+    });
+    return this;
+  }
+}
+
+/**
+ * Output help information if help flags specified
+ *
+ * @param {Command} cmd - command to output help for
+ * @param {Array} args - array of options to search for help flags
+ * @api private
+ */
+
+function outputHelpIfRequested(cmd, args) {
+  const helpOption = cmd._hasHelpOption && args.find(arg => arg === cmd._helpLongFlag || arg === cmd._helpShortFlag);
+  if (helpOption) {
+    cmd.outputHelp();
+    // (Do not have all displayed text available so only passing placeholder.)
+    cmd._exit(0, 'commander.helpDisplayed', '(outputHelp)');
+  }
+}
+
+/**
+ * Scan arguments and increment port number for inspect calls (to avoid conflicts when spawning new command).
+ *
+ * @param {string[]} args - array of arguments from node.execArgv
+ * @returns {string[]}
+ * @api private
+ */
+
+function incrementNodeInspectorPort(args) {
+  // Testing for these options:
+  //  --inspect[=[host:]port]
+  //  --inspect-brk[=[host:]port]
+  //  --inspect-port=[host:]port
+  return args.map((arg) => {
+    if (!arg.startsWith('--inspect')) {
+      return arg;
+    }
+    let debugOption;
+    let debugHost = '127.0.0.1';
+    let debugPort = '9229';
+    let match;
+    if ((match = arg.match(/^(--inspect(-brk)?)$/)) !== null) {
+      // e.g. --inspect
+      debugOption = match[1];
+    } else if ((match = arg.match(/^(--inspect(-brk|-port)?)=([^:]+)$/)) !== null) {
+      debugOption = match[1];
+      if (/^\d+$/.test(match[3])) {
+        // e.g. --inspect=1234
+        debugPort = match[3];
+      } else {
+        // e.g. --inspect=localhost
+        debugHost = match[3];
+      }
+    } else if ((match = arg.match(/^(--inspect(-brk|-port)?)=([^:]+):(\d+)$/)) !== null) {
+      // e.g. --inspect=localhost:1234
+      debugOption = match[1];
+      debugHost = match[3];
+      debugPort = match[4];
+    }
+
+    if (debugOption && debugPort !== '0') {
+      return `${debugOption}=${debugHost}:${parseInt(debugPort) + 1}`;
+    }
+    return arg;
+  });
+}
+
+/**
+ * @param {Command} startCommand
+ * @returns {Command[]}
+ * @api private
+ */
+
+function getCommandAndParents(startCommand) {
+  const result = [];
+  for (let command = startCommand; command; command = command.parent) {
+    result.push(command);
+  }
+  return result;
+}
+
+exports.Command = Command;
diff --git a/node_modules/commander/lib/error.js b/node_modules/commander/lib/error.js
new file mode 100644
index 0000000..e7cde9c
--- /dev/null
+++ b/node_modules/commander/lib/error.js
@@ -0,0 +1,45 @@
+// @ts-check
+
+/**
+ * CommanderError class
+ * @class
+ */
+class CommanderError extends Error {
+  /**
+   * Constructs the CommanderError class
+   * @param {number} exitCode suggested exit code which could be used with process.exit
+   * @param {string} code an id string representing the error
+   * @param {string} message human-readable description of the error
+   * @constructor
+   */
+  constructor(exitCode, code, message) {
+    super(message);
+    // properly capture stack trace in Node.js
+    Error.captureStackTrace(this, this.constructor);
+    this.name = this.constructor.name;
+    this.code = code;
+    this.exitCode = exitCode;
+    this.nestedError = undefined;
+  }
+}
+
+/**
+ * InvalidArgumentError class
+ * @class
+ */
+class InvalidArgumentError extends CommanderError {
+  /**
+   * Constructs the InvalidArgumentError class
+   * @param {string} [message] explanation of why argument is invalid
+   * @constructor
+   */
+  constructor(message) {
+    super(1, 'commander.invalidArgument', message);
+    // properly capture stack trace in Node.js
+    Error.captureStackTrace(this, this.constructor);
+    this.name = this.constructor.name;
+  }
+}
+
+exports.CommanderError = CommanderError;
+exports.InvalidArgumentError = InvalidArgumentError;
diff --git a/node_modules/commander/lib/help.js b/node_modules/commander/lib/help.js
new file mode 100644
index 0000000..14e0fb9
--- /dev/null
+++ b/node_modules/commander/lib/help.js
@@ -0,0 +1,464 @@
+const { humanReadableArgName } = require('./argument.js');
+
+/**
+ * TypeScript import types for JSDoc, used by Visual Studio Code IntelliSense and `npm run typescript-checkJS`
+ * https://www.typescriptlang.org/docs/handbook/jsdoc-supported-types.html#import-types
+ * @typedef { import("./argument.js").Argument } Argument
+ * @typedef { import("./command.js").Command } Command
+ * @typedef { import("./option.js").Option } Option
+ */
+
+// @ts-check
+
+// Although this is a class, methods are static in style to allow override using subclass or just functions.
+class Help {
+  constructor() {
+    this.helpWidth = undefined;
+    this.sortSubcommands = false;
+    this.sortOptions = false;
+    this.showGlobalOptions = false;
+  }
+
+  /**
+   * Get an array of the visible subcommands. Includes a placeholder for the implicit help command, if there is one.
+   *
+   * @param {Command} cmd
+   * @returns {Command[]}
+   */
+
+  visibleCommands(cmd) {
+    const visibleCommands = cmd.commands.filter(cmd => !cmd._hidden);
+    if (cmd._hasImplicitHelpCommand()) {
+      // Create a command matching the implicit help command.
+      const [, helpName, helpArgs] = cmd._helpCommandnameAndArgs.match(/([^ ]+) *(.*)/);
+      const helpCommand = cmd.createCommand(helpName)
+        .helpOption(false);
+      helpCommand.description(cmd._helpCommandDescription);
+      if (helpArgs) helpCommand.arguments(helpArgs);
+      visibleCommands.push(helpCommand);
+    }
+    if (this.sortSubcommands) {
+      visibleCommands.sort((a, b) => {
+        // @ts-ignore: overloaded return type
+        return a.name().localeCompare(b.name());
+      });
+    }
+    return visibleCommands;
+  }
+
+  /**
+   * Compare options for sort.
+   *
+   * @param {Option} a
+   * @param {Option} b
+   * @returns number
+   */
+  compareOptions(a, b) {
+    const getSortKey = (option) => {
+      // WYSIWYG for order displayed in help. Short used for comparison if present. No special handling for negated.
+      return option.short ? option.short.replace(/^-/, '') : option.long.replace(/^--/, '');
+    };
+    return getSortKey(a).localeCompare(getSortKey(b));
+  }
+
+  /**
+   * Get an array of the visible options. Includes a placeholder for the implicit help option, if there is one.
+   *
+   * @param {Command} cmd
+   * @returns {Option[]}
+   */
+
+  visibleOptions(cmd) {
+    const visibleOptions = cmd.options.filter((option) => !option.hidden);
+    // Implicit help
+    const showShortHelpFlag = cmd._hasHelpOption && cmd._helpShortFlag && !cmd._findOption(cmd._helpShortFlag);
+    const showLongHelpFlag = cmd._hasHelpOption && !cmd._findOption(cmd._helpLongFlag);
+    if (showShortHelpFlag || showLongHelpFlag) {
+      let helpOption;
+      if (!showShortHelpFlag) {
+        helpOption = cmd.createOption(cmd._helpLongFlag, cmd._helpDescription);
+      } else if (!showLongHelpFlag) {
+        helpOption = cmd.createOption(cmd._helpShortFlag, cmd._helpDescription);
+      } else {
+        helpOption = cmd.createOption(cmd._helpFlags, cmd._helpDescription);
+      }
+      visibleOptions.push(helpOption);
+    }
+    if (this.sortOptions) {
+      visibleOptions.sort(this.compareOptions);
+    }
+    return visibleOptions;
+  }
+
+  /**
+   * Get an array of the visible global options. (Not including help.)
+   *
+   * @param {Command} cmd
+   * @returns {Option[]}
+   */
+
+  visibleGlobalOptions(cmd) {
+    if (!this.showGlobalOptions) return [];
+
+    const globalOptions = [];
+    for (let parentCmd = cmd.parent; parentCmd; parentCmd = parentCmd.parent) {
+      const visibleOptions = parentCmd.options.filter((option) => !option.hidden);
+      globalOptions.push(...visibleOptions);
+    }
+    if (this.sortOptions) {
+      globalOptions.sort(this.compareOptions);
+    }
+    return globalOptions;
+  }
+
+  /**
+   * Get an array of the arguments if any have a description.
+   *
+   * @param {Command} cmd
+   * @returns {Argument[]}
+   */
+
+  visibleArguments(cmd) {
+    // Side effect! Apply the legacy descriptions before the arguments are displayed.
+    if (cmd._argsDescription) {
+      cmd._args.forEach(argument => {
+        argument.description = argument.description || cmd._argsDescription[argument.name()] || '';
+      });
+    }
+
+    // If there are any arguments with a description then return all the arguments.
+    if (cmd._args.find(argument => argument.description)) {
+      return cmd._args;
+    }
+    return [];
+  }
+
+  /**
+   * Get the command term to show in the list of subcommands.
+   *
+   * @param {Command} cmd
+   * @returns {string}
+   */
+
+  subcommandTerm(cmd) {
+    // Legacy. Ignores custom usage string, and nested commands.
+    const args = cmd._args.map(arg => humanReadableArgName(arg)).join(' ');
+    return cmd._name +
+      (cmd._aliases[0] ? '|' + cmd._aliases[0] : '') +
+      (cmd.options.length ? ' [options]' : '') + // simplistic check for non-help option
+      (args ? ' ' + args : '');
+  }
+
+  /**
+   * Get the option term to show in the list of options.
+   *
+   * @param {Option} option
+   * @returns {string}
+   */
+
+  optionTerm(option) {
+    return option.flags;
+  }
+
+  /**
+   * Get the argument term to show in the list of arguments.
+   *
+   * @param {Argument} argument
+   * @returns {string}
+   */
+
+  argumentTerm(argument) {
+    return argument.name();
+  }
+
+  /**
+   * Get the longest command term length.
+   *
+   * @param {Command} cmd
+   * @param {Help} helper
+   * @returns {number}
+   */
+
+  longestSubcommandTermLength(cmd, helper) {
+    return helper.visibleCommands(cmd).reduce((max, command) => {
+      return Math.max(max, helper.subcommandTerm(command).length);
+    }, 0);
+  }
+
+  /**
+   * Get the longest option term length.
+   *
+   * @param {Command} cmd
+   * @param {Help} helper
+   * @returns {number}
+   */
+
+  longestOptionTermLength(cmd, helper) {
+    return helper.visibleOptions(cmd).reduce((max, option) => {
+      return Math.max(max, helper.optionTerm(option).length);
+    }, 0);
+  }
+
+  /**
+   * Get the longest global option term length.
+   *
+   * @param {Command} cmd
+   * @param {Help} helper
+   * @returns {number}
+   */
+
+  longestGlobalOptionTermLength(cmd, helper) {
+    return helper.visibleGlobalOptions(cmd).reduce((max, option) => {
+      return Math.max(max, helper.optionTerm(option).length);
+    }, 0);
+  }
+
+  /**
+   * Get the longest argument term length.
+   *
+   * @param {Command} cmd
+   * @param {Help} helper
+   * @returns {number}
+   */
+
+  longestArgumentTermLength(cmd, helper) {
+    return helper.visibleArguments(cmd).reduce((max, argument) => {
+      return Math.max(max, helper.argumentTerm(argument).length);
+    }, 0);
+  }
+
+  /**
+   * Get the command usage to be displayed at the top of the built-in help.
+   *
+   * @param {Command} cmd
+   * @returns {string}
+   */
+
+  commandUsage(cmd) {
+    // Usage
+    let cmdName = cmd._name;
+    if (cmd._aliases[0]) {
+      cmdName = cmdName + '|' + cmd._aliases[0];
+    }
+    let parentCmdNames = '';
+    for (let parentCmd = cmd.parent; parentCmd; parentCmd = parentCmd.parent) {
+      parentCmdNames = parentCmd.name() + ' ' + parentCmdNames;
+    }
+    return parentCmdNames + cmdName + ' ' + cmd.usage();
+  }
+
+  /**
+   * Get the description for the command.
+   *
+   * @param {Command} cmd
+   * @returns {string}
+   */
+
+  commandDescription(cmd) {
+    // @ts-ignore: overloaded return type
+    return cmd.description();
+  }
+
+  /**
+   * Get the subcommand summary to show in the list of subcommands.
+   * (Fallback to description for backwards compatibility.)
+   *
+   * @param {Command} cmd
+   * @returns {string}
+   */
+
+  subcommandDescription(cmd) {
+    // @ts-ignore: overloaded return type
+    return cmd.summary() || cmd.description();
+  }
+
+  /**
+   * Get the option description to show in the list of options.
+   *
+   * @param {Option} option
+   * @return {string}
+   */
+
+  optionDescription(option) {
+    const extraInfo = [];
+
+    if (option.argChoices) {
+      extraInfo.push(
+        // use stringify to match the display of the default value
+        `choices: ${option.argChoices.map((choice) => JSON.stringify(choice)).join(', ')}`);
+    }
+    if (option.defaultValue !== undefined) {
+      // default for boolean and negated more for programmer than end user,
+      // but show true/false for boolean option as may be for hand-rolled env or config processing.
+      const showDefault = option.required || option.optional ||
+        (option.isBoolean() && typeof option.defaultValue === 'boolean');
+      if (showDefault) {
+        extraInfo.push(`default: ${option.defaultValueDescription || JSON.stringify(option.defaultValue)}`);
+      }
+    }
+    // preset for boolean and negated are more for programmer than end user
+    if (option.presetArg !== undefined && option.optional) {
+      extraInfo.push(`preset: ${JSON.stringify(option.presetArg)}`);
+    }
+    if (option.envVar !== undefined) {
+      extraInfo.push(`env: ${option.envVar}`);
+    }
+    if (extraInfo.length > 0) {
+      return `${option.description} (${extraInfo.join(', ')})`;
+    }
+
+    return option.description;
+  }
+
+  /**
+   * Get the argument description to show in the list of arguments.
+   *
+   * @param {Argument} argument
+   * @return {string}
+   */
+
+  argumentDescription(argument) {
+    const extraInfo = [];
+    if (argument.argChoices) {
+      extraInfo.push(
+        // use stringify to match the display of the default value
+        `choices: ${argument.argChoices.map((choice) => JSON.stringify(choice)).join(', ')}`);
+    }
+    if (argument.defaultValue !== undefined) {
+      extraInfo.push(`default: ${argument.defaultValueDescription || JSON.stringify(argument.defaultValue)}`);
+    }
+    if (extraInfo.length > 0) {
+      const extraDescripton = `(${extraInfo.join(', ')})`;
+      if (argument.description) {
+        return `${argument.description} ${extraDescripton}`;
+      }
+      return extraDescripton;
+    }
+    return argument.description;
+  }
+
+  /**
+   * Generate the built-in help text.
+   *
+   * @param {Command} cmd
+   * @param {Help} helper
+   * @returns {string}
+   */
+
+  formatHelp(cmd, helper) {
+    const termWidth = helper.padWidth(cmd, helper);
+    const helpWidth = helper.helpWidth || 80;
+    const itemIndentWidth = 2;
+    const itemSeparatorWidth = 2; // between term and description
+    function formatItem(term, description) {
+      if (description) {
+        const fullText = `${term.padEnd(termWidth + itemSeparatorWidth)}${description}`;
+        return helper.wrap(fullText, helpWidth - itemIndentWidth, termWidth + itemSeparatorWidth);
+      }
+      return term;
+    }
+    function formatList(textArray) {
+      return textArray.join('\n').replace(/^/gm, ' '.repeat(itemIndentWidth));
+    }
+
+    // Usage
+    let output = [`Usage: ${helper.commandUsage(cmd)}`, ''];
+
+    // Description
+    const commandDescription = helper.commandDescription(cmd);
+    if (commandDescription.length > 0) {
+      output = output.concat([helper.wrap(commandDescription, helpWidth, 0), '']);
+    }
+
+    // Arguments
+    const argumentList = helper.visibleArguments(cmd).map((argument) => {
+      return formatItem(helper.argumentTerm(argument), helper.argumentDescription(argument));
+    });
+    if (argumentList.length > 0) {
+      output = output.concat(['Arguments:', formatList(argumentList), '']);
+    }
+
+    // Options
+    const optionList = helper.visibleOptions(cmd).map((option) => {
+      return formatItem(helper.optionTerm(option), helper.optionDescription(option));
+    });
+    if (optionList.length > 0) {
+      output = output.concat(['Options:', formatList(optionList), '']);
+    }
+
+    if (this.showGlobalOptions) {
+      const globalOptionList = helper.visibleGlobalOptions(cmd).map((option) => {
+        return formatItem(helper.optionTerm(option), helper.optionDescription(option));
+      });
+      if (globalOptionList.length > 0) {
+        output = output.concat(['Global Options:', formatList(globalOptionList), '']);
+      }
+    }
+
+    // Commands
+    const commandList = helper.visibleCommands(cmd).map((cmd) => {
+      return formatItem(helper.subcommandTerm(cmd), helper.subcommandDescription(cmd));
+    });
+    if (commandList.length > 0) {
+      output = output.concat(['Commands:', formatList(commandList), '']);
+    }
+
+    return output.join('\n');
+  }
+
+  /**
+   * Calculate the pad width from the maximum term length.
+   *
+   * @param {Command} cmd
+   * @param {Help} helper
+   * @returns {number}
+   */
+
+  padWidth(cmd, helper) {
+    return Math.max(
+      helper.longestOptionTermLength(cmd, helper),
+      helper.longestGlobalOptionTermLength(cmd, helper),
+      helper.longestSubcommandTermLength(cmd, helper),
+      helper.longestArgumentTermLength(cmd, helper)
+    );
+  }
+
+  /**
+   * Wrap the given string to width characters per line, with lines after the first indented.
+   * Do not wrap if insufficient room for wrapping (minColumnWidth), or string is manually formatted.
+   *
+   * @param {string} str
+   * @param {number} width
+   * @param {number} indent
+   * @param {number} [minColumnWidth=40]
+   * @return {string}
+   *
+   */
+
+  wrap(str, width, indent, minColumnWidth = 40) {
+    // Full \s characters, minus the linefeeds.
+    const indents = ' \\f\\t\\v\u00a0\u1680\u2000-\u200a\u202f\u205f\u3000\ufeff';
+    // Detect manually wrapped and indented strings by searching for line break followed by spaces.
+    const manualIndent = new RegExp(`[\\n][${indents}]+`);
+    if (str.match(manualIndent)) return str;
+    // Do not wrap if not enough room for a wrapped column of text (as could end up with a word per line).
+    const columnWidth = width - indent;
+    if (columnWidth < minColumnWidth) return str;
+
+    const leadingStr = str.slice(0, indent);
+    const columnText = str.slice(indent).replace('\r\n', '\n');
+    const indentString = ' '.repeat(indent);
+    const zeroWidthSpace = '\u200B';
+    const breaks = `\\s${zeroWidthSpace}`;
+    // Match line end (so empty lines don't collapse),
+    // or as much text as will fit in column, or excess text up to first break.
+    const regex = new RegExp(`\n|.{1,${columnWidth - 1}}([${breaks}]|$)|[^${breaks}]+?([${breaks}]|$)`, 'g');
+    const lines = columnText.match(regex) || [];
+    return leadingStr + lines.map((line, i) => {
+      if (line === '\n') return ''; // preserve empty lines
+      return ((i > 0) ? indentString : '') + line.trimEnd();
+    }).join('\n');
+  }
+}
+
+exports.Help = Help;
diff --git a/node_modules/commander/lib/option.js b/node_modules/commander/lib/option.js
new file mode 100644
index 0000000..d61fc5f
--- /dev/null
+++ b/node_modules/commander/lib/option.js
@@ -0,0 +1,331 @@
+const { InvalidArgumentError } = require('./error.js');
+
+// @ts-check
+
+class Option {
+  /**
+   * Initialize a new `Option` with the given `flags` and `description`.
+   *
+   * @param {string} flags
+   * @param {string} [description]
+   */
+
+  constructor(flags, description) {
+    this.flags = flags;
+    this.description = description || '';
+
+    this.required = flags.includes('<'); // A value must be supplied when the option is specified.
+    this.optional = flags.includes('['); // A value is optional when the option is specified.
+    // variadic test ignores <value,...> et al which might be used to describe custom splitting of single argument
+    this.variadic = /\w\.\.\.[>\]]$/.test(flags); // The option can take multiple values.
+    this.mandatory = false; // The option must have a value after parsing, which usually means it must be specified on command line.
+    const optionFlags = splitOptionFlags(flags);
+    this.short = optionFlags.shortFlag;
+    this.long = optionFlags.longFlag;
+    this.negate = false;
+    if (this.long) {
+      this.negate = this.long.startsWith('--no-');
+    }
+    this.defaultValue = undefined;
+    this.defaultValueDescription = undefined;
+    this.presetArg = undefined;
+    this.envVar = undefined;
+    this.parseArg = undefined;
+    this.hidden = false;
+    this.argChoices = undefined;
+    this.conflictsWith = [];
+    this.implied = undefined;
+  }
+
+  /**
+   * Set the default value, and optionally supply the description to be displayed in the help.
+   *
+   * @param {any} value
+   * @param {string} [description]
+   * @return {Option}
+   */
+
+  default(value, description) {
+    this.defaultValue = value;
+    this.defaultValueDescription = description;
+    return this;
+  }
+
+  /**
+   * Preset to use when option used without option-argument, especially optional but also boolean and negated.
+   * The custom processing (parseArg) is called.
+   *
+   * @example
+   * new Option('--color').default('GREYSCALE').preset('RGB');
+   * new Option('--donate [amount]').preset('20').argParser(parseFloat);
+   *
+   * @param {any} arg
+   * @return {Option}
+   */
+
+  preset(arg) {
+    this.presetArg = arg;
+    return this;
+  }
+
+  /**
+   * Add option name(s) that conflict with this option.
+   * An error will be displayed if conflicting options are found during parsing.
+   *
+   * @example
+   * new Option('--rgb').conflicts('cmyk');
+   * new Option('--js').conflicts(['ts', 'jsx']);
+   *
+   * @param {string | string[]} names
+   * @return {Option}
+   */
+
+  conflicts(names) {
+    this.conflictsWith = this.conflictsWith.concat(names);
+    return this;
+  }
+
+  /**
+   * Specify implied option values for when this option is set and the implied options are not.
+   *
+   * The custom processing (parseArg) is not called on the implied values.
+   *
+   * @example
+   * program
+   *   .addOption(new Option('--log', 'write logging information to file'))
+   *   .addOption(new Option('--trace', 'log extra details').implies({ log: 'trace.txt' }));
+   *
+   * @param {Object} impliedOptionValues
+   * @return {Option}
+   */
+  implies(impliedOptionValues) {
+    let newImplied = impliedOptionValues;
+    if (typeof impliedOptionValues === 'string') {
+      // string is not documented, but easy mistake and we can do what user probably intended.
+      newImplied = { [impliedOptionValues]: true };
+    }
+    this.implied = Object.assign(this.implied || {}, newImplied);
+    return this;
+  }
+
+  /**
+   * Set environment variable to check for option value.
+   *
+   * An environment variable is only used if when processed the current option value is
+   * undefined, or the source of the current value is 'default' or 'config' or 'env'.
+   *
+   * @param {string} name
+   * @return {Option}
+   */
+
+  env(name) {
+    this.envVar = name;
+    return this;
+  }
+
+  /**
+   * Set the custom handler for processing CLI option arguments into option values.
+   *
+   * @param {Function} [fn]
+   * @return {Option}
+   */
+
+  argParser(fn) {
+    this.parseArg = fn;
+    return this;
+  }
+
+  /**
+   * Whether the option is mandatory and must have a value after parsing.
+   *
+   * @param {boolean} [mandatory=true]
+   * @return {Option}
+   */
+
+  makeOptionMandatory(mandatory = true) {
+    this.mandatory = !!mandatory;
+    return this;
+  }
+
+  /**
+   * Hide option in help.
+   *
+   * @param {boolean} [hide=true]
+   * @return {Option}
+   */
+
+  hideHelp(hide = true) {
+    this.hidden = !!hide;
+    return this;
+  }
+
+  /**
+   * @api private
+   */
+
+  _concatValue(value, previous) {
+    if (previous === this.defaultValue || !Array.isArray(previous)) {
+      return [value];
+    }
+
+    return previous.concat(value);
+  }
+
+  /**
+   * Only allow option value to be one of choices.
+   *
+   * @param {string[]} values
+   * @return {Option}
+   */
+
+  choices(values) {
+    this.argChoices = values.slice();
+    this.parseArg = (arg, previous) => {
+      if (!this.argChoices.includes(arg)) {
+        throw new InvalidArgumentError(`Allowed choices are ${this.argChoices.join(', ')}.`);
+      }
+      if (this.variadic) {
+        return this._concatValue(arg, previous);
+      }
+      return arg;
+    };
+    return this;
+  }
+
+  /**
+   * Return option name.
+   *
+   * @return {string}
+   */
+
+  name() {
+    if (this.long) {
+      return this.long.replace(/^--/, '');
+    }
+    return this.short.replace(/^-/, '');
+  }
+
+  /**
+   * Return option name, in a camelcase format that can be used
+   * as a object attribute key.
+   *
+   * @return {string}
+   * @api private
+   */
+
+  attributeName() {
+    return camelcase(this.name().replace(/^no-/, ''));
+  }
+
+  /**
+   * Check if `arg` matches the short or long flag.
+   *
+   * @param {string} arg
+   * @return {boolean}
+   * @api private
+   */
+
+  is(arg) {
+    return this.short === arg || this.long === arg;
+  }
+
+  /**
+   * Return whether a boolean option.
+   *
+   * Options are one of boolean, negated, required argument, or optional argument.
+   *
+   * @return {boolean}
+   * @api private
+   */
+
+  isBoolean() {
+    return !this.required && !this.optional && !this.negate;
+  }
+}
+
+/**
+ * This class is to make it easier to work with dual options, without changing the existing
+ * implementation. We support separate dual options for separate positive and negative options,
+ * like `--build` and `--no-build`, which share a single option value. This works nicely for some
+ * use cases, but is tricky for others where we want separate behaviours despite
+ * the single shared option value.
+ */
+class DualOptions {
+  /**
+   * @param {Option[]} options
+   */
+  constructor(options) {
+    this.positiveOptions = new Map();
+    this.negativeOptions = new Map();
+    this.dualOptions = new Set();
+    options.forEach(option => {
+      if (option.negate) {
+        this.negativeOptions.set(option.attributeName(), option);
+      } else {
+        this.positiveOptions.set(option.attributeName(), option);
+      }
+    });
+    this.negativeOptions.forEach((value, key) => {
+      if (this.positiveOptions.has(key)) {
+        this.dualOptions.add(key);
+      }
+    });
+  }
+
+  /**
+   * Did the value come from the option, and not from possible matching dual option?
+   *
+   * @param {any} value
+   * @param {Option} option
+   * @returns {boolean}
+   */
+  valueFromOption(value, option) {
+    const optionKey = option.attributeName();
+    if (!this.dualOptions.has(optionKey)) return true;
+
+    // Use the value to deduce if (probably) came from the option.
+    const preset = this.negativeOptions.get(optionKey).presetArg;
+    const negativeValue = (preset !== undefined) ? preset : false;
+    return option.negate === (negativeValue === value);
+  }
+}
+
+/**
+ * Convert string from kebab-case to camelCase.
+ *
+ * @param {string} str
+ * @return {string}
+ * @api private
+ */
+
+function camelcase(str) {
+  return str.split('-').reduce((str, word) => {
+    return str + word[0].toUpperCase() + word.slice(1);
+  });
+}
+
+/**
+ * Split the short and long flag out of something like '-m,--mixed <value>'
+ *
+ * @api private
+ */
+
+function splitOptionFlags(flags) {
+  let shortFlag;
+  let longFlag;
+  // Use original very loose parsing to maintain backwards compatibility for now,
+  // which allowed for example unintended `-sw, --short-word` [sic].
+  const flagParts = flags.split(/[ |,]+/);
+  if (flagParts.length > 1 && !/^[[<]/.test(flagParts[1])) shortFlag = flagParts.shift();
+  longFlag = flagParts.shift();
+  // Add support for lone short flag without significantly changing parsing!
+  if (!shortFlag && /^-[^-]$/.test(longFlag)) {
+    shortFlag = longFlag;
+    longFlag = undefined;
+  }
+  return { shortFlag, longFlag };
+}
+
+exports.Option = Option;
+exports.splitOptionFlags = splitOptionFlags;
+exports.DualOptions = DualOptions;
diff --git a/node_modules/commander/lib/suggestSimilar.js b/node_modules/commander/lib/suggestSimilar.js
new file mode 100644
index 0000000..9a4066c
--- /dev/null
+++ b/node_modules/commander/lib/suggestSimilar.js
@@ -0,0 +1,100 @@
+const maxDistance = 3;
+
+function editDistance(a, b) {
+  // https://en.wikipedia.org/wiki/Damerau–Levenshtein_distance
+  // Calculating optimal string alignment distance, no substring is edited more than once.
+  // (Simple implementation.)
+
+  // Quick early exit, return worst case.
+  if (Math.abs(a.length - b.length) > maxDistance) return Math.max(a.length, b.length);
+
+  // distance between prefix substrings of a and b
+  const d = [];
+
+  // pure deletions turn a into empty string
+  for (let i = 0; i <= a.length; i++) {
+    d[i] = [i];
+  }
+  // pure insertions turn empty string into b
+  for (let j = 0; j <= b.length; j++) {
+    d[0][j] = j;
+  }
+
+  // fill matrix
+  for (let j = 1; j <= b.length; j++) {
+    for (let i = 1; i <= a.length; i++) {
+      let cost = 1;
+      if (a[i - 1] === b[j - 1]) {
+        cost = 0;
+      } else {
+        cost = 1;
+      }
+      d[i][j] = Math.min(
+        d[i - 1][j] + 1, // deletion
+        d[i][j - 1] + 1, // insertion
+        d[i - 1][j - 1] + cost // substitution
+      );
+      // transposition
+      if (i > 1 && j > 1 && a[i - 1] === b[j - 2] && a[i - 2] === b[j - 1]) {
+        d[i][j] = Math.min(d[i][j], d[i - 2][j - 2] + 1);
+      }
+    }
+  }
+
+  return d[a.length][b.length];
+}
+
+/**
+ * Find close matches, restricted to same number of edits.
+ *
+ * @param {string} word
+ * @param {string[]} candidates
+ * @returns {string}
+ */
+
+function suggestSimilar(word, candidates) {
+  if (!candidates || candidates.length === 0) return '';
+  // remove possible duplicates
+  candidates = Array.from(new Set(candidates));
+
+  const searchingOptions = word.startsWith('--');
+  if (searchingOptions) {
+    word = word.slice(2);
+    candidates = candidates.map(candidate => candidate.slice(2));
+  }
+
+  let similar = [];
+  let bestDistance = maxDistance;
+  const minSimilarity = 0.4;
+  candidates.forEach((candidate) => {
+    if (candidate.length <= 1) return; // no one character guesses
+
+    const distance = editDistance(word, candidate);
+    const length = Math.max(word.length, candidate.length);
+    const similarity = (length - distance) / length;
+    if (similarity > minSimilarity) {
+      if (distance < bestDistance) {
+        // better edit distance, throw away previous worse matches
+        bestDistance = distance;
+        similar = [candidate];
+      } else if (distance === bestDistance) {
+        similar.push(candidate);
+      }
+    }
+  });
+
+  similar.sort((a, b) => a.localeCompare(b));
+  if (searchingOptions) {
+    similar = similar.map(candidate => `--${candidate}`);
+  }
+
+  if (similar.length > 1) {
+    return `\n(Did you mean one of ${similar.join(', ')}?)`;
+  }
+  if (similar.length === 1) {
+    return `\n(Did you mean ${similar[0]}?)`;
+  }
+  return '';
+}
+
+exports.suggestSimilar = suggestSimilar;