code: def test_to_dict(self, cls):
      mapping_in = cls(
          {
              f"a{i}": cls({f"b{j}": 0 for j in range(2)})
              for i in range(10)
          }
      )
      mapping_out = data_structures.to_dict(mapping_in)
      self.assertEqual(mapping_in, mapping_out)
      self.assertIs(type(mapping_out), dict)
      self.assertIsNot(mapping_in, mapping_out)
      for key in mapping_in:
          self.assertIs(type(mapping_out[key]), dict)
          self.assertIsNot(mapping_in[key], mapping_out[key])
  
imports: import collections
  import copy
  import pickle
  import threading
  from absl.testing import absltest
  from absl.testing import parameterized
  import cloudpickle
  import dill
  from haiku._src import data_structures
  import jax
  import tree
label_desc: Use image node_id 1 for calling the DataStructuresTest obj's underlying member method code with example usage: obj.test_to_dict(cls) without return types