human
Solve the following python programming problem given the following code:
@ pytest.fixture 
def mock_message_thread_builder(mock_message_builder, mock_profile_builder) : 
    counter = itertools.count () 
    next (counter) 
    def _build_mock_message_thread(id = None, message_count = 2, initiator = 'initiator', respondent = 'respondent', **kwargs) : 
        if (id is None) : 
            id = next (counter) 
messages = [mock_message_builder (content = '{0}'.format (i), sender = (respondent if (i % 2) else initiator), recipient = (initiator if (i % 2) else respondent)) for i in range (message_count)] 
        kwargs.setdefault ('datetime', datetime.datetime (year = 2014, day = 2, month = 4)) 
        message_thread = mock.MagicMock (id = id, messages = messages, ** kwargs) 
        message_thread.initiator = mock_profile_builder (initiator) 
        message_thread.respondent = mock_profile_builder (respondent) 
        return message_thread 
return mock_message_builder 

    
    

    Fix the buggy line: return mock_message_builder
assistant
#Here is Python code to fix the buggy line: return mock_message_builder
.

return def _build_mock_message_thread(