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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 transmit_ack_bpdu(self):
 """ Send Topology Change Ack BPDU. """

        ack_flags = 0b10000001
        bpdu_data = self._generate_config_bpdu(ack_flags)
        self.ofctl.send_packet_out(self.ofport.port_no, bpdu_data)