code: def decoder_iter(video_file):
      cap = cv2.VideoCapture(video_file)
      assert cap.isOpened(), "Cannot open video file: {}".format(
          video_file
      )
  
      frame_id = 0
      while True:
          ret, frame = cap.read()
          if ret:
              yield frame_id, frame[:, :, ::-1]
              frame_id += 1
          else:
              break
  
file_path: gluon-cv/scripts/tracking/smot/demo.py
imports: import os
  import argparse
  import logging
  import numpy
  import cv2
  from gluoncv.model_zoo.smot import smot_tracker
  from gluoncv.model_zoo.smot.tracktors import GluonSSDMultiClassTracktor
label_desc: Use image node_id 3 for calling a global function with example usage: decoder_iter(video_file) without return types