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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 publish_command_failure(self, duration, failure, command_name, request_id, connection_id, op_id=None):
 """Publish a CommandFailedEvent to all command listeners. :Parameters: - `duration`: The command duration as a datetime.timedelta. - `failure`: The server reply document or failure description document. - `command_name`: The command name. - `request_id`: The request id for this operation. - `connection_id`: The address (host, port) of the server this command was sent to. - `op_id`: The (optional) operation id for this operation. """

        if op_id is None:
            op_id = request_id
        event = CommandFailedEvent(
            duration, failure, command_name, request_id, connection_id, op_id)
        for subscriber in self.__command_listeners:
            try:
                subscriber.failed(event)
            except Exception:
                _handle_exception()