def create(self, performance=None):
show = Show.get(self.read('show_key'))
if not show: raise Exception("That show doesn't exist.")
venue = Venue.get(self.read('venue_key'))
if not venue: raise Exception("That venue doesn't exist.")
year = int(self.read('year'))
month = int(self.read('month'))
day = int(self.read('day'))
hour = int(self.read('hour'))
minute = int(self.read('minute'))
Performance(show = show,
venue = venue,
utc_date_time = datetime.datetime(year, month, day, hour, minute) - venue.city.get_timedelta()
).put()
self.get()
