为什么这个 function 返回无？

Question

我正在处理客户端 - 服务器项目。 我正在开发一项功能，让用户可以选择向多个用户发送消息。

我有 2 个功能：

def broadcast(self, TalkingCurrentClient, message):
       WhomMessageClient = self.ChoosingClientToSendMessage(message)
       if WhomMessageClient is not None:
           ##################################
           if WhomMessageClient is not isinstance(WhomMessageClient, list):
               ##################################
               if TalkingCurrentClient == WhomMessageClient:
                   SerializedDataToBytes(WhomMessageClient, message)
               if TalkingCurrentClient != WhomMessageClient:
                   SerializedDataToBytes(WhomMessageClient, message)
       #############################################################
       elif WhomMessageClient is isinstance(WhomMessageClient, list):
           for ClientToSend in WhomMessageClient:
               if ClientToSend != TalkingCurrentClient:
                   SerializedDataToBytes(ClientToSend, message)
               else:
                   SerializedDataToBytes(ClientToSend, message)
       #############################################################
       else:
           for client in self.clientsList:
               if client != TalkingCurrentClient:
                   SerializedDataToBytes(client, message)
               else:
                   SerializedDataToBytes(client, message)

这个 function 应该接受单个用户名或用户列表，这取决于用户的选择。 function 从第二个 function 调用 ChooseClientToSendMessage ChoosingClientToSendMessage(message)

但是，当我选择单个客户端（用户） WhomMessageClient从 function 2 获取正确的客户端时，但是当我发送客户端列表时，我得到一个无值。

这是 function 2：

 def ChoosingClientToSendMessage(self, message):
        if message.recipient is not None and message.recipient != 'None':
            if isinstance(message.recipient, list):
                for ClientToAddToList in message.recipient:
                    ChoosingMultipleClientToSend = []
                    index = self.ConnectionsList.index(ClientToAddToList)
                    ChoosingMultipleClientToSend.append(self.clientsList[index])
                if ChoosingMultipleClientToSend:
                    return ChoosingMultipleClientToSend
            ################################################################
            else:
                index = self.ConnectionsList.index(message.recipient)
                ClientThatWhomMessage = self.clientsList[index]
                print(ClientThatWhomMessage)
                if ClientThatWhomMessage:
                    return ClientThatWhomMessage
        return None