'Constructor
@param calendar: the calendar
@param dtfmt: the date/time format'

def __init__(self, calendar, dtfmt=None):

    if (not calendar):
        raise TypeError(('Invalid    calendar:    %s    (%s)' % (calendar, type(calendar))))
    self.calendar = calendar.calendar
    self.grammar = None
    self.rules = None
    self.set_format(dtfmt)
