human
Solve the following python programming problem given the following code:
def on_recv(self, callback) : 
    '
        Register an on_recv callback
        ' 
    if (callback is None) : 
        return self.message_client.on_recv (self) 
@ tornado.gen.coroutine 
    def wrap_callback(body) : 
        if (not isinstance (body, dict)) : 
            body = msgpack.loads (body) 
            if six.PY3 : 
                body = salt.transport.frame.decode_embedded_strs (body) 
ret = (yield self._decode_payload (body)) 
        callback (ret) 
return self.message_client.on_recv (wrap_callback) 

    
    

    Fix the buggy line: return self.message_client.on_recv (self)
assistant
#Here is Python code to fix the buggy line: return self.

return self.message_client.on_recv (callback)