def isLeapYear(year: int) -> bool:
    """Return True if year is a leap year, False otherwise."""
    if year <= 0:
        return False
    #          4 years v     400 years v    not 100 years v
    return not (year % 4 or (year % 400 and not year % 100))


print("Testing isLeapYear()...", end="")
assert isLeapYear(2024) == True
assert isLeapYear(2023) == False
assert isLeapYear(2020) == True
assert isLeapYear(1900) == False  # divisible by 100 but not by 400
assert isLeapYear(2000) == True  # divisible by 100 but also by 400
assert isLeapYear(-2024) == False  # non-positive years are not leap years
assert isLeapYear(0) == False  # non-positive years are not leap years
print("Passed!")