code: def add_carrier(self, carrier_record, power_state, aux_data_records=None):
          
          carrier = Carrier(carrier_record, power_state)
          if aux_data_records is not None:
              for aux in RecordList(aux_data_records):
                  carrier.auxiliary_data_records.append(aux)
          self.carriers.append(carrier)
docs: Add a new carrier to the handover request message.
  
          :param carrier_record: a record providing carrier information
          :param power_state: a string describing the carrier power state
          :param aux_data_records: list of auxiliary data records
          :type carrier_record: :class:`nfc.ndef.Record`
          :type power_state: :class:`str`
          :type aux_data_records: :class:`~nfc.ndef.record.RecordList`
          
          >>> hr = nfc.ndef.HandoverRequestMessage(version="1.2")
          >>> hr.add_carrier(some_carrier_record, "active")