text: """
  Common constants used in tjunlp.
  """
  
  # class _Const:
  #     class ConstError(TypeError):
  #         pass
  #
  #     class ConstCaseError(ConstError):
  #         pass
  #
  #     def __setattr__(self, name, value):
  #         if name in self.__dict__:
  #             raise self.ConstError("Can't change const(%s) value" % name)
  #         if not name.isupper():
  #             raise self.ConstCaseError("Const name %s is not all uppercase" % name)
  #
  #         self.__dict__[name] = value
  #
  #     def __getitem__(self, key):
  #         if key in self.__dict__:
  #             return self.__dict__[key]
  #         else:
  #             raise self.ConstError("Can't return const %s, No Existing Key!" % key)
  #
  #     def __delattr__(self, name):
  #         if name in self.__dict__:
  #             raise self.ConstError("Can't unbind const(%s)" % name)
  #         raise NameError(name)
  #
  #
  # const = _Const()
  
  # dataset
  KEY_TRAIN, KEY_DEV, KEY_TEST = "train", "dev", "test"
  PRETRAIN_POSTFIX = "_PRETRAINED"
  
  # vocabulary
  DEFAULT_FIELD = "tokens"
  