Get the port ID when given a port name

        :param str port_name: port name
        :param str device_id: device ID
        :param list nodes: list of nodes from :py:meth:`generate_nodes`
        :return: port ID
        :rtype: int

def port_id_from_name(port_name, device_id, nodes):
        """
        Get the port ID when given a port name

        :param str port_name: port name
        :param str device_id: device ID
        :param list nodes: list of nodes from :py:meth:`generate_nodes`
        :return: port ID
        :rtype: int
        """
        port_id = None
        for node in nodes:
            if device_id == node['id']:
                for port in node['ports']:
                    if port_name == port['name']:
                        port_id = port['id']
                        break
                break
        return port_id