code: def __len__(self):
      return len(self.img_list)
  
imports: from PIL import Image
  import os
  import torch.utils.data
  import torchvision.transforms
  from torch.utils.data.sampler import Sampler
  import numpy
label_desc: Use image node_id 3 for calling the Mix_Dataset_112_paired obj's underlying member method code with example usage: obj.__len__() and returns: len