@classmethod
def _check_pretrained_file_names(cls, pretrained_file_name):
    """Checks if a pre-trained token embedding file name is valid.


        Parameters
        ----------
        pretrained_file_name : str
            The pre-trained token embedding file.
        """
    embedding_name = cls.__name__.lower()
    if pretrained_file_name not in cls.pretrained_file_name_sha1:
        raise KeyError(
            'Cannot find pretrained file %s for token embedding %s. Valid pretrained files for embedding %s: %s'
             % (pretrained_file_name, embedding_name, embedding_name, ', '.
            join(cls.pretrained_file_name_sha1.keys())))
