<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def pop(self, count=None):
        '''Passing in the queue from which to pull items, the current time,
        when the locks for these returned items should expire, and the number
        of items to be popped off.'''
        results = [Job(self.client, **job) for job in json.loads(
            self.client('pop', self.name, self.worker_name, count or 1))]
        if count is None:
            return (len(results) and results[0]) or None
        return results