docs: def change_default(
      kls,
      key,
      new_default,
      new_converter=None,
      new_reference_value=None,
  ):
      """return a new configman Option object that is a copy of an existing one,
      giving the new one a different default value"""
      an_option = kls.get_required_config()[key].copy()
      an_option.default = new_default
      if new_converter:
          an_option.from_string_converter = new_converter
      if new_reference_value:
          an_option.reference_value_from = new_reference_value
      return an_option