def group(self):
        """
        The group this event belongs to.  Adding the event as a child of a
        group automatically assigns the event to that group.
        """
        retval = None
        parent = self.get_parent()
        Group = get_group_model()
        if issubclass(parent.specific_class, Group):
            retval = parent.specific
        if retval is None:
            retval = self.group_page
        return retval
The group this event belongs to.  Adding the event as a child of a
        group automatically assigns the event to that group.