code: def DEFINE_alias(name, original_name, flag_values=FLAGS, module_name=None):
    if original_name not in flag_values:
      raise UnrecognizedFlagError(original_name)
    flag = flag_values[original_name]
    class _Parser(ArgumentParser):
      def parse(self, argument):
        flag.parse(argument)
        return flag.value
    class _FlagAlias(Flag):
      @property
      def value(self):
        return flag.value
      @value.setter
      def value(self, value):
        flag.value = value
    help_msg = 'Alias for --%s.' % flag.name
    DEFINE_flag(_FlagAlias(_Parser(), flag.serializer, name, flag.default,
                           help_msg, boolean=flag.boolean),
                flag_values, module_name)