No vertices:
0, 0
Comparing 5 separate vertices and one 5-element cluster:
0, 4
Comparing ((6, 1), (2,4), (3,5,0)) with ((2), (6,0,3), (4,5), (1)):
3, 2
Comparing ((0,1), (), 2) with ((0), (), (1,2))
1, 1

Expected to fail nicely:

Differently sized clusterings
