def get_true_capacity(self):
        """Get the capacity for the scheduled activity, taking into account activity defaults and
        overrides."""

        c = self.capacity
        if c is not None:
            return c
        else:
            if self.rooms.count() == 0 and self.activity.default_capacity:
                # use activity-level override
                return self.activity.default_capacity

            rooms = self.get_true_rooms()
            return EighthRoom.total_capacity_of_rooms(rooms)
Get the capacity for the scheduled activity, taking into account activity defaults and
        overrides.