def _reset_fields(self):
        """
        Before each uodate call, reset fields first
        """
        self._matched_idx = set()
        self._matched_ID = set()
        self._untracked_prev_idx = set(range(len(self._prev_instances)))

        Before each uodate call, reset fields first
        
EVA-01/det/detectron2/tracking/bbox_iou_tracker.py