def test_keys():
mv = MultiVector()
mi1 = Multiindex([1, 2, 3])
mi2 = Multiindex([1, 2, 4])
mv[mi1] = FlatVector([3, 4, 5])
mv[mi2] = FlatVector([3, 4, 7])
keys = mv.keys()
assert_equal(sorted(keys), sorted([mi1, mi2]))
inds = mv.active_indices()
assert_equal(sorted(inds), sorted([mi1, mi2]))
