'Get the first day of the week for this calendar'

@property
def first_dow(self):

    calendar = self.calendar
    first_dow = calendar._first_dow
    if (first_dow is None):
        first_dow = current.deployment_settings.get_L10n_firstDOW()
        if (first_dow is None):
            first_dow = calendar.FIRST_DOW
        calendar._first_dow = first_dow
    return first_dow
