human
Solve the following python programming problem given the following code:
def _test_call_raising_error_1(self, trans_id) : 
    (p, t, dmx, mux) = self.build_proto () 
    dmx.inject (3, 0, const.RTMP_COMMAND, 1, encode_amf ('breakdown1', trans_id)) 
    def check_messages(_result) : 
        self.assertEquals (self.messages, [('!1', 0, 1, ())]) 
def verify_sent_messages(_result) : 
        msgs = muxer_messages (mux) 
        error_tuple = ('Artificially.Failed', 'error') 
        self.assertEquals (len (msgs), 1) 
        msg = msgs [0] 
        self.assertEquals ((msg [0 : 3] + msg [4 :]), (0, chunks.MSG_COMMAND, 1, False)) 
        args = msg [3] 
        self.assertEquals (len (args), 4) 
        self.assertEquals (args [: 3], ['_error', trans_id, None]) 
        self.assertIsInstance (args [3], Object) 
        self.assertEquals ((args [3].code, args [3].level), error_tuple) 
d = defer.Deferred () 
    d.addCallback (check_messages) 
    d.addCallback (verify_sent_messages) 
    d.addCallback ((lambda _ : self.assertFalse (t.disconnecting))) 
    reactor.callLater (0, check_messages.callback, None) 
    return d 

    
    

    Fix the buggy line: reactor.callLater (0, check_messages.callback, None)
assistant
#Here is Python code to fix the buggy line: reactor.

reactor.callLater (0, d.callback, None)