code: def save_checkpoint(net, args, epoch, mIoU, is_best=False):
      """Save Checkpoint"""
      filename = "epoch_%04d_mIoU_%2.4f.params" % (epoch, mIoU)
      filepath = os.path.join(args.save_dir, filename)
      net.save_parameters(filepath)
      if is_best:
          shutil.copyfile(
              filename, os.path.join(args.save_dir, "model_best.params")
          )
  
imports: import os
  import logging
  import shutil
  import argparse
  import numpy
  from tqdm import tqdm
  import mxnet
  from mxnet import gluon, autograd
  from mxnet.gluon.data.vision import transforms
  import gluoncv
  from gluoncv.loss import *
  from gluoncv.utils import makedirs, LRScheduler, LRSequential
  from gluoncv.model_zoo.segbase import *
  from gluoncv.model_zoo import get_model
  from gluoncv.utils.parallel import *
  from gluoncv.data import get_segmentation_dataset
label_desc: Use image node_id 2 for calling a global function with example usage: save_checkpoint(net, args, epoch, mIoU, is_best) without return types