Given a set of objects, separate them by the boxes they belong to and return a dict.

def _separate_objects_by_boxes(self, objects: Set[Object]) -> Dict[Box, List[Object]]:
        """
        Given a set of objects, separate them by the boxes they belong to and return a dict.
        """
        objects_per_box: Dict[Box, List[Object]] = defaultdict(list)
        for box in self.boxes:
            for object_ in objects:
                if object_ in box.objects:
                    objects_per_box[box].append(object_)
        return objects_per_box