code: def test_json_null_infer() -> None:
      json = BytesIO(
          bytes(
              """
      [
        {
          "a": 1,
          "b": null
        }
      ]
      """,
              "UTF-8",
          )
      )
  
      assert pl.read_json(json).schema == OrderedDict(
          {"a": pl.Int64, "b": pl.Null}
      )
  
imports: from __future__ import annotations
  import datetime
  import io
  import json
  from collections import OrderedDict
  from io import BytesIO
  from typing import TYPE_CHECKING, Any
  import pytest
  import polars
  from polars.testing import assert_frame_equal
label_desc: Use image node_id 23 for calling a global function with example usage: test_json_null_infer() without return types