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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 _get_primary_address(self, mac_address, node_list):
 """ Uses the _get_aggregated_node_list structure to find the primary mac address associated to a secondary one, if none is found returns itself. """

        for local_addresses in node_list:
            if mac_address in local_addresses:
                return local_addresses[0]
        return mac_address