code: def ref(self, history):
      return history.to_list()
  
imports: import pickle
  import time
  import multiprocessing
  from functools import partial
  import numpy
  import pytest
  import torch
  from torch.distributed import TCPStore
  from sklearn.datasets import make_classification
label_desc: Use image node_id 3 for calling the TestHistory obj's underlying member method code with example usage: obj.ref(history) and returns: history