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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def close(self, reply_code=0, reply_text='', class_id=0, method_id=0):
        '''
        Close this channel.  Routes to channel.close.
        '''
        # In the off chance that we call this twice. A good example is if
        # there's an error in close listeners and so we're still inside a
        # single call to process_frames, which will try to close this channel
        # if there's an exception.
        if hasattr(self, 'channel'):
            self.channel.close(reply_code, reply_text, class_id, method_id)