'Registers entity to put to datastore.
Args:
entity: an entity or model instance to put.'

def put(self, entity):

    actual_entity = _normalize_entity(entity)
    entity_size = len(actual_entity._ToPb().Encode())
    if ((self.puts.length >= MAX_ENTITY_COUNT) or ((self.puts.size + entity_size) > self.max_pool_size)):
        self.__flush_puts()
    self.puts.append(actual_entity, entity_size)
