def test_walk_deep_map():
w, x, y, z = variables("w, x, y, z")
sub = Substitution({x: "b", z: y, w: Map().insert(x, z).insert("a", "b")})
value = sub.walk_deep(w)
assert value == Map().insert("b", y).insert("a", "b")
def test_walk_deep():
w, x, y, z = variables("w, x, y, z")
sub = Substitution({x: "b", z: y, w: (x, "e", z)})
value = sub.walk_deep(w)
assert value == ("b", "e", y)