def set_partition(self, partition):
        """
        Store the partition in self.partition, and
        move the old self.partition into self.prev_partition
        """
        assert len(partition) == self.numgrp
        self.partition, self.prev_partition = partition, self.partition
def set_partition ( self , partition ) : assert len ( partition ) == self . numgrp self . partition , self . prev_partition = partition , self . partition
Store the partition in self.partition, and
        move the old self.partition into self.prev_partition