code: def __len__(self):
      return len(self.dataset)
  
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 the SRDataset obj's underlying member method code with example usage: obj.__len__() and returns: len