def __str__(self):
        '''\
Included for testing purposes only.
All information needed from the union find data structure can be attained
using find.'''
        sets = {}
        for i in xrange(len(self.objects_to_num)):
            sets[i] = []
        for i in self.objects_to_num:
            sets[self.objects_to_num[self.find(i)]].append(i)
        out = []
        for i in sets.itervalues():
            if i:
                out.append(repr(i))
        return ', '.join(out)
Included for testing purposes only.
All information needed from the union find data structure can be attained
using find.
recipes/Python/215912_Union_Find_data_structure/recipe-215912.py