code: def test_activate_decimals() -> None:
      with pl.Config() as cfg:
          cfg.activate_decimals(True)
          assert os.environ.get("POLARS_ACTIVATE_DECIMAL") == "1"
          cfg.activate_decimals(False)
          assert "POLARS_ACTIVATE_DECIMAL" not in os.environ
  
imports: from __future__ import annotations
  import os
  from pathlib import Path
  from typing import Any, Iterator
  import pytest
  import polars
  import polars.polars
  from polars.config import _POLARS_CFG_ENV_VARS
label_desc: Use image node_id 16 for calling a global function with example usage: test_activate_decimals() without return types