code: def __init__(self, cfg, mode="eval"):
      self.cfg = cfg
      assert mode.lower() in [
          "test",
          "eval",
      ], "mode should be 'test' or 'eval'"
      self.mode = mode.lower()
      self.optimizer = None
  
      # build model
      self.model = create(cfg.architecture)
  
      self.status = {}
      self.start_epoch = 0
  
imports: import os
  import cv2
  import glob
  import paddle
  import numpy
  import collections
  from ppdet.utils.checkpoint import load_weight, load_pretrain_weight
  from ppdet.metrics import Metric, MOTMetric, KITTIMOTMetric
  import ppdet.utils.stats
  from ppdet.engine.callbacks import Callback, ComposeCallback
  from ppdet.core.workspace import create
  from ppdet.utils.logger import setup_logger
  from .dataset import MOTVideoStream, MOTImageStream
  from .modeling.mot.utils import Detection, get_crops, scale_coords, clip_box
  from .modeling.mot import visualization
  from .utils import Timer
label_desc: Use image node_id 1 to create a new StreamTracker object from inherited base classes: object with example: obj = StreamTracker(cfg, mode)