code: def test_items(self):
      f_map = FlatMap(
          {"foo": {"b": {"c": 1}, "d": {"e": 2}}, "bar": {"c": 1}}
      )
      items = list(f_map.items())
      self.assertEqual(
          items[0], ("foo", {"b": {"c": 1}, "d": {"e": 2}})
      )
      self.assertEqual(items[1], ("bar", {"c": 1}))
      self.assertEqual(items, list(zip(f_map.keys(), f_map.values())))
  
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 23 for calling the FlatMappingTest obj's underlying member method code with example usage: obj.test_items() without return types