docstr: Ensure that an informative exception is raised on key conflict.
docstr_tok: ["Ensure","that","an","informative","exception","is","raised","on","key","conflict","."]
code: def test_raises_error_on_key_conflict(self):
      """Ensure that an informative exception is raised on key conflict."""
      with self.assertRaisesRegex(TypeError, r"Cannot unflatten dict"):
          unflatten_dict({"a": 1, "a/b": 2, "a/c": 3})
  
      with self.assertRaisesRegex(TypeError, r"Cannot unflatten dict"):
          unflatten_dict({"a/b": 2, "a/b/c": 3})
  
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 8 for calling the UnflattenDictTest obj's underlying member method code with example usage: obj.test_raises_error_on_key_conflict() without return types