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)