code: def test_output_type(self):
      in_ = OrderedDict({"a": {"b": 1}, "c": {"d": 2}, "e": 3})
      out = flatten_dict(in_)
      assert type(in_) is type(out)
  
imports: import copy
  from collections import OrderedDict
  import pytest
  import sys
  import unittest
  from unittest.mock import patch
  from ray.tune.utils.util import wait_for_gpu
  from ray.tune.utils.util import flatten_dict, unflatten_dict, unflatten_list_dict
label_desc: Use image node_id 1 for calling the FlattenDictTest obj's underlying member method code with example usage: obj.test_output_type() without return types