def leapyear(year):
    """
    leapyear determines if the given year is a leap year or not.
    year must be positive, and must not be abbreviated; i.e.
    89 is 89 A.D. not 1989.

    Args:
        year

    Returns:
        True if a leap year, False if not a leap year
    """

    assert(year >= 0)

    if ((year % 4 == 0 and year % 100 != 0) or year % 400 == 0):
        return True
    else:
        return False