code: def checkpoint():
      model_out_path = "model_epoch_{}.pth".format(trainer.state.epoch)
      torch.save(model, model_out_path)
      print("Checkpoint saved to {}".format(model_out_path))
  
imports: import argparse
  import torch
  import torch.nn
  import torch.optim
  import torchvision
  from model import Net
  from torch.utils.data import DataLoader
  from torchvision.transforms.functional import center_crop, resize, to_tensor
  from ignite.contrib.handlers import ProgressBar
  from ignite.engine import Engine, Events
  from ignite.handlers import BasicTimeProfiler
  from ignite.metrics import PSNR
label_desc: Use image node_id 4 for calling a global function with example usage: checkpoint() without return types