def connect(self): 
        try:
            self.connection = pymongo.Connection(self.host, self.port)
            self.db = self.connection[self.name]
        except AutoReconnect:
            raise DatabaseException("It's not possible connect to the database")
def __init__(self, masked_tokens=None, name='num_tokens', dtype=tf.int64):
    self._masked_tokens = masked_tokens or []
    super().__init__(name, dtype)