d = {1: 10, "a": "ABC", (3,4): 5}
assert 1 in d.keys()
assert (1) in d.keys()
assert "a" in d.keys()
assert (3,4) in d.keys()
assert () not in d.keys()
assert 10 not in d.keys()
assert (1, 10) not in d.keys()
assert "abc" not in d.keys()
assert ((3,4),5) not in d.keys()