human
Solve the following python programming problem given the following code:
def _post_connect(self) : 
    'Greeting stuff' 
    init_event = Event () 
    error = [None] 
    def ok_cb(id, capabilities) : 
        self._id = id 
        self._server_capabilities = capabilities 
        init_event.set () 
def err_cb(err) : 
        error [0] = err 
        init_event.set () 
listener = HelloHandler (ok_cb, err_cb) 
    self.add_listener (error) 
    self.send (HelloHandler.build (self._client_capabilities, self._device_handler)) 
    logger.debug ('starting main loop') 
    self.start () 
    init_event.wait (60) 
    if (not init_event.is_set ()) : 
        raise SessionError ('Capability exchange timed out') 
self.remove_listener (listener) 
    if error [0] : 
        raise error [0] 
logger.info (('initialized: session-id=%s | server_capabilities=%s' % (self._id, self._server_capabilities))) 

    
    

    Fix the buggy line: self.add_listener (error)
assistant
#Here is Python program to fix the buggy line: self.

self.add_listener (listener)