'Derives parameters from a given training text, or uses the parameters
given. Repeated calls to this method destroy previous parameters. For
incremental training, instantiate a separate PunktTrainer instance.'

def train(self, train_text, verbose=False):

    if (not isinstance(train_text, string_types)):
        return train_text
    return PunktTrainer(train_text, lang_vars=self._lang_vars, token_cls=self._Token).get_params()
