No vertices:
Mutual: 0 asymmetric: 0 null: 0

One vertex:
Mutual: 0 asymmetric: 0 null: 0

Two vertices:
Mutual: 0 asymmetric: 1 null: 0

Graph with loops and multiple edges:
Mutual: 1 asymmetric: 4 null: 10

Same graph, but undirected:
Mutual: 5 asymmetric: 0 null: 10

