helpOption(flags, description) {
    // Support enabling/disabling built-in help option.
    if (typeof flags === 'boolean') {
      if (flags) {
        if (this._helpOption === null) this._helpOption = undefined; // reenable
        if (this._defaultOptionGroup) {
          // make the option to store the group
          this._initOptionGroup(this._getHelpOption());
        }
      } else {
        this._helpOption = null; // disable
      }
      return this;
    }

    // Customise flags and description.
    this._helpOption = this.createOption(
      flags ?? '-h, --help',
      description ?? 'display help for command',
    );
    // init group unless lazy create
    if (flags || description) this._initOptionGroup(this._helpOption);

    return this;
  }
You can pass in flags and a description to customise the built-in help option.
Pass in false to disable the built-in help option.

@example
program.helpOption('-?, --help' 'show help'); // customise
program.helpOption(false); // disable

@param {(string | boolean)} flags
@param {string} [description]
@return {Command} `this` command for chaining