def fizzBuzz(n: int) -> str | int:
    """Return the fizzbuzz string for n."""
    str = ""
    if n % 3 == 0:
        str += "fizz"
    if n % 5 == 0:
        b = ""
        if len(str):
            b = "B"
        else:
            b = "b"
        str += f"{b}uzz"
    return str or n


print("Testing fizzBuzz()...", end="")
assert fizzBuzz(21) == "fizz"
assert fizzBuzz(25) == "buzz"
assert fizzBuzz(30) == "fizzBuzz"
assert fizzBuzz(31) == 31

# should work for negatives:
assert fizzBuzz(-240) == "fizzBuzz"
assert fizzBuzz(-245) == "buzz"
assert fizzBuzz(-246) == "fizz"
assert fizzBuzz(-247) == -247

# and 0 (which is a multiple of 3 and a multiple of 5):
assert fizzBuzz(0) == "fizzBuzz"
print("Passed!")