code: def test_categorical_update_lengths() -> None:
      with pl.StringCache():
          s1 = pl.Series(["", ""], dtype=pl.Categorical)
          s2 = pl.Series([None, "", ""], dtype=pl.Categorical)
  
      s = pl.concat([s1, s2], rechunk=False)
      assert s.null_count() == 1
      assert s.len() == 5
  
imports: from __future__ import annotations
  import contextlib
  import io
  import operator
  from typing import TYPE_CHECKING, Any, Callable, Literal
  import pytest
  import polars
  from polars import StringCache
  from polars.exceptions import CategoricalRemappingWarning, StringCacheMismatchError
  from polars.testing import assert_frame_equal, assert_series_equal
label_desc: Use image node_id 38 for calling a global function with example usage: test_categorical_update_lengths() without return types