def __getitem__(self, message_class):
    if self.items not in message_class.MESSAGE_TYPE_ID:
      raise KeyError(message_class)
    item = self.items[message_class.MESSAGE_TYPE_ID]
    if item.Parse(message_class):
      return item.message
    else:
      raise KeyError(message_class)
dataset/ETHPy150Open AppScale/appscale/AppServer/google/net/proto/message_set.py/MessageSet.__getitem__/swapped operands of `not in`