optionsGroup(heading) {
    if (heading === undefined) return this._defaultOptionGroup ?? '';
    this._defaultOptionGroup = heading;
    return this;
  }
Set/get the default help group heading for options added to this command.
(This does not override a group set directly on the option using .helpGroup().)

@example
program
  .optionsGroup('Development Options:')
  .option('-d, --debug', 'output extra debugging')
  .option('-p, --profile', 'output profiling information')

@param {string} [heading]
@returns {Command | string}