docstr: test for json2vals
          
code: def test_json2vals(self):
      """test for json2vals"""
      json_search_space = {
          "optimizer": {"_type": "choice", "_value": ["Adam", "SGD"]},
          "learning_rate": {
              "_type": "choice",
              "_value": [0.0001, 0.001, 0.002, 0.005, 0.01],
          },
      }
      out_y = dict()
      vals = {
          "optimizer": {"_index": 0, "_value": "Adam"},
          "learning_rate": {"_index": 1, "_value": 0.001},
      }
      json2vals(json_search_space, vals, out_y)
      self.assertEqual(out_y["root[optimizer]-choice"], 0)
      self.assertEqual(out_y["root[learning_rate]-choice"], 1)
  
file_path: nni/test/ut/sdk/test_hyperopt_tuner.py
imports: from unittest import TestCase, main
  import hyperopt
  from nni.algorithms.hpo.hyperopt_tuner import json2space, json2parameter, json2vals, HyperoptTuner
label_desc: Use image node_id 3 for calling the HyperoptTunerTestCase obj's underlying member method code with example usage: obj.test_json2vals() without return types