Finnish holidays

holiday.py

def is_holiday(d):
    """Check whether the given dateutil.date is a Finnish national holiday"""
    import dateutil.easter
    from datetime import date, timedelta as td
    assert isinstance(d, date)
    md = '{}.{}'.format(d.day, d.month)
    y = d.year
    # Fixed-date holidays
    if md in '1.1 6.1 1.5 6.12 24.12 25.12 26.12'.split(): return True
    # Finnish midsummer (eve on Fri the 19..25th, day on Sat the 20..26th)
    if date(y,6,19) <= d <= date(y,6,25) and d.weekday() == 4: return True
    if date(y,6,20) <= d <= date(y,6,26) and d.weekday() == 5: return True
    # All Saints (Saturday)
    if date(y,10,31) <= d <= date(y,11,6) and d.weekday() == 5: return True
    # Easter etc.
    e = dateutil.easter.easter(d.year)
    if d in [e - td(2), e, e + td(1), e + td(39), e + td(49)]: return True
    return False