def is_day_of_week(date, day_of_week):
    """Determine if a date is a specific day of the week.

    Args:
        date: datetime.date instance
        day_of_week: str, either full day of the week name or abbr
            Eg 'Mon', 'Monday'

    Returns:
        True if the date matches the weekday.
    """
    fmt = '%A' if len(day_of_week) > 3 else '%a'
    return date.strftime(fmt) == day_of_week