def start(self, **kwargs):
    assert (self.instance.status in (self.instance.STATUS_INSTANTIATED, self.instance.STATUS_SCHEDULED))
    if (not self.instance.started_at):
        self.instance.started_at = timezone.now()
    self.instance.status = self.instance.STATUS_STARTED
def start(self, **kwargs):
    assert (self.instance.status in (self.instance.STATUS_INSTANTIATED, self.instance.STATUS_SCHEDULED))
    if (not self.instance.started_at):
        self.instance.started_at = timezone.now()
    self.instance.status = self.instance.STATUS_STARTED