code: def log_validation():
      evaluator.run(
          testing_data_loader, epoch_length=validate_epoch_length
      )
      metrics = evaluator.state.metrics
      print(
          f"Epoch: {trainer.state.epoch}, Avg. PSNR: {metrics['psnr']} dB"
      )
  
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 3 for calling a global function with example usage: log_validation() without return types