def valid_date(date):
    try:
        date = date.strip()
        month, day, year = date.split('-')
        month, day, year = int(month), int(day), int(year)
        if month < 1 or month > 12:
            return False
        if month in [1,3,5,7,8,10,12] and day < 1 or day > 31:
            return False
        if month in [4,6,9,11] and day < 1 or day > 30:
            return False
        if month == 2 and day < 1 or day > 29:
            return False
    except:
        return False
    return True
def truncate_number(number: float) -> float:
    """ Given a positive floating point number, it can be decomposed into
    and integer part (largest integer smaller than given number) and decimals
    (leftover part always smaller than 1).
    Return the decimal part of the number.
    >>> truncate_number(3.5)
    0.5
    """
    return number % 1.0