code: def test_case(self):
      a = {
          "a": 1,
          "c": 5,
          "Jack": "jill",
          "pick": "axe",
          "Array": [1, 5, 6, 9],
          "tuple": (83, 12, 3),
          "crate": "dog",
          "zeak": "oh",
      }
      self.assertEqual(
          '{"Array": [1, 5, 6, 9], "Jack": "jill", "a": 1, "c": 5, "crate": "dog", "pick": "axe", "tuple": [83, 12, 3], "zeak": "oh"}',
          json.dumps(a, item_sort_key=itemgetter(0)),
      )
      self.assertEqual(
          '{"a": 1, "Array": [1, 5, 6, 9], "c": 5, "crate": "dog", "Jack": "jill", "pick": "axe", "tuple": [83, 12, 3], "zeak": "oh"}',
          json.dumps(a, item_sort_key=lambda kv: kv[0].lower()),
      )
  
file_path: catboost/contrib/python/simplejson/py2/simplejson/tests/test_item_sort_key.py
imports: from unittest import TestCase
  import simplejson
  from operator import itemgetter
label_desc: Use image node_id 2 for calling the TestItemSortKey obj's underlying member method code with example usage: obj.test_case() without return types