@classmethod
def _serialize_keys(cls, hash_key, range_key=None):
    """
        Serializes the hash and range keys

        :param hash_key: The hash key value
        :param range_key: The range key value
        """
    hash_key = cls._hash_key_attribute().serialize(hash_key)
    if range_key is not None:
        range_key = cls._range_key_attribute().serialize(range_key)
    return hash_key, range_key
