human
Solve the following python programming problem given the following code:
def _processQueue(self) : 
    '
        Process the next item in queue.
        ' 
    self._call = None 
    def reschedule(_) : 
        self._call = self._clock.callLater (0, self._processQueue) 
def processItem(obj) : 
        d = self.callback (obj) 
        d.addErrback (log.err) 
        d.addCallback (reschedule) 
        return d 
if (self.pending and (not self.paused)) : 
        obj = self.pending.popleft () 
        processItem (obj) 
else : 
        if (not self.waiting) : 
            def canceller(_) : 
                self.waiting = None 
def trapCancelledError(failure) : 
                failure.trap (defer.CancelledError) 
d = defer.Deferred (canceller = canceller) 
            d.addCallback (reschedule) 
            d.addErrback (trapCancelledError) 
            d.addErrback (log.err) 
            self.waiting = d 
else : 
            pass 

    
    

    Fix the buggy line: d.addCallback (reschedule)
assistant
#Here is Python code to fix the buggy line: d.

d.addCallback (processItem)