code: def test_set_use_global_context__on():
      with proj_context_env():
          set_use_global_context(True)
          assert pyproj._datadir._USE_GLOBAL_CONTEXT is True
  
imports: import logging
  import os
  from contextlib import contextmanager
  from pathlib import Path
  from unittest.mock import patch
  import pytest
  import pyproj._datadir
  from pyproj import CRS, Transformer, get_codes, set_use_global_context
  from pyproj._datadir import _pyproj_global_context_initialize
  from pyproj.datadir import DataDirError, append_data_dir, get_data_dir, get_user_data_dir, set_data_dir
  from pyproj.enums import PJType
  from pyproj.exceptions import CRSError
  from test.conftest import proj_env
label_desc: Use image node_id 20 for calling a global function with example usage: test_set_use_global_context__on() without return types