import datetime


class IsoWeek(datetime.date):
    """Datetime representing the Monday of an ISO-8601 week.
    """
    pass


class TeachingWeek(datetime.date):
    """Datetime representing the Monday of a teaching week.
    """
    pass


class BreakWeek(datetime.date):
    """Datetime representing the Monday of a break (e.g., mid-semester) week.
    """
    pass