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())))
Checks if a pre-trained token embedding file name is valid.


        Parameters
        ----------
        pretrained_file_name : str
            The pre-trained token embedding file.