code: def test_multi_transform_empty(self, mt):
      for empty_tree in ({}, [], (), AttrMap()):
          with self.subTest(type(empty_tree).__name__):
              f = mt(
                  lambda: (lambda: None, empty_tree)
              )  # pylint: disable=cell-var-from-loop
              f.init(None)
              self.assertEqual(f.apply, empty_tree)
  
imports: import inspect
  from typing import Optional, Union
  from absl.testing import absltest
  from absl.testing import parameterized
  from haiku._src import base
  from haiku._src import multi_transform
  from haiku._src import transform
  from haiku._src import typing
  import jax
  import jax.numpy
  import numpy
label_desc: Use image node_id 1 for calling the MultiTransformTest obj's underlying member method code with example usage: obj.test_multi_transform_empty(mt) without return types