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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 add_carrier(self, carrier_record, power_state, aux_data_records=None):
 """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` """

        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)