code: def test_tree_map(self, tree_map):
      f = FlatMap(dict(a=1, b=dict(c=2)))
      p = tree_map("v: {}".format, f)
      self.assertEqual(type(p), FlatMap)
      self.assertEqual(
          p._to_mapping(), {"a": "v: 1", "b": {"c": "v: 2"}}
      )
  
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 9 for calling the FlatMappingTest obj's underlying member method code with example usage: obj.test_tree_map(tree_map) without return types