code: def __init__(self):
      self._pred_clusters = defaultdict(
          list
      )  # {classname: List[_Instance]}
      self._gt_clusters = defaultdict(lambda: defaultdict(list))
  
imports: import torchnet
  from typing import NamedTuple, Dict, Any, List, Tuple
  import torch
  import numpy
  from torch_scatter import scatter_add
  from collections import OrderedDict, defaultdict
  from torch_points3d.models.model_interface import TrackerInterface
  from torch_points3d.metrics.segmentation_tracker import SegmentationTracker
  from torch_points3d.metrics.base_tracker import BaseTracker, meter_value
  from torch_points3d.models.panoptic.structures import PanopticResults, PanopticLabels
  from torch_points_kernels import instance_iou
  from .box_detection.ap import voc_ap
label_desc: Use image node_id 1 to create a new InstanceAPMeter object  with example: obj = InstanceAPMeter()