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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 calc_mb_ports(self):
 """ Add the default ports to add to a router """

        model = self.device_info['model']
        chassis = self.device_info['chassis']
        num_ports = MODEL_MATRIX[model][chassis]['ports']
        ports = []

        if num_ports > 0:
            port_type = MODEL_MATRIX[model][chassis]['type']

            # Create the ports dict
            for i in range(num_ports):
                port_temp = {'name': PORT_TYPES[port_type] + '0/' + str(i),
                             'id': self.port_id,
                             'port_number': i,
                             'slot_number': 0}
                ports.append(port_temp)
                self.port_id += 1
        self.node['ports'].extend(ports)