code: def __call__(self, batch_examples):
      feed_dict = {}
      feed_dict["data"] = batch_examples
      feed_dict["labels"] = [i for i in range(len(batch_examples))]
      return feed_dict
  
imports: import time
  import unittest
  import json
  import os
  import random
  from pgl.utils.data.dataset import Dataset, StreamDataset
  from pgl.utils.data.dataloader import Dataloader
label_desc: Use image node_id 2 for calling the Collate_fn obj's underlying member method code with example usage: obj.__call__(batch_examples) and returns: feed_dict