'Asserts that the matching is what we expect from the bipartite graph
constructed in the :meth:`setup` fixture.'

def check_match(self, matching):

    M = matching
    matched_vertices = frozenset(itertools.chain(*M.items()))
    assert (matched_vertices == (frozenset(range(12)) - {1, 10}))
    assert all(((u == M[M[u]]) for u in range(12) if (u in M)))
