code: def __getitem__(self, i):
      return dict(a=np.random.random(size=10), b=i)
  
imports: from unittest import TestCase
  import jax.numpy
  import numpy
  import optax
  import pytest
  import elegy
label_desc: Use image node_id 2 for calling the DS_custom_batch_fn obj's underlying member method code with example usage: obj.__getitem__(i) and returns: dict