code: def test_check_result_serialization_to_json(iris_dataset):
      import json
  
      result = ColumnsInfo(n_top_columns=4).run(iris_dataset)
      serialized_result = result.to_json()
  
      assert_that(serialized_result, instance_of(str))
      json.loads(serialized_result)
  
imports: import contextlib
  import io
  import pathlib
  import typing
  from unittest.mock import Mock, patch
  import jsonpickle
  import pandas
  import plotly.express
  import plotly.io
  from hamcrest import all_of, any_of, assert_that, calling, equal_to, greater_than, has_entries, has_length, instance_of, is_, matches_regexp, only_contains, raises
  from ipywidgets import VBox, Widget
  from deepchecks.core.check_result import CheckFailure, CheckResult
  from deepchecks.core.errors import DeepchecksValueError
  from deepchecks.tabular.checks import ColumnsInfo, MixedNulls
  from deepchecks.utils.json_utils import from_json
  from tests.common import DummyCheck, create_check_result, create_suite_result, instance_of_ipython_formatter
label_desc: Use image node_id 4 for calling a global function with example usage: test_check_result_serialization_to_json(iris_dataset) without return types