code: def save_checkpoint(net, opt, epoch, is_best=False):
      """Save Checkpoint"""
      filename = "epoch_%d.params" % (epoch)
      filepath = os.path.join(opt.save_dir, filename)
      net.save_parameters(filepath)
      if is_best:
          shutil.copyfile(
              filename, os.path.join(opt.save_dir, "model_best.params")
          )
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  import argparse
  import logging
  import os
  import time
  import numpy
  import mxnet
  from mxnet import gluon, nd, autograd
  from mxnet.contrib import amp
  from gluoncv.utils import LRScheduler, LRSequential, split_and_load
  from gluoncv.data.tracking_data.track import TrkDataset
  from gluoncv.model_zoo import get_model
  from gluoncv.loss import SiamRPNLoss
label_desc: Use image node_id 5 for calling a global function with example usage: save_checkpoint(net, opt, epoch, is_best) without return types