code: def test_cpl_debug_false(tmpdir):
      """Setting CPL_DEBUG=False results in no GDAL debug messages."""
      log = logging.getLogger("rasterio._gdal")
      log.setLevel(logging.DEBUG)
      logfile = str(tmpdir.join("test.log"))
      fh = logging.FileHandler(logfile)
      log.addHandler(fh)
  
      with rasterio.Env(CPL_DEBUG=False):
          with rasterio.open("tests/data/RGB.byte.tif"):
              pass
  
      # Expect no debug messages from GDAL.
      log = open(logfile).read()
      assert "GDAL: GDALOpen(tests/data/RGB.byte.tif" not in log
  
imports: import logging
  import rasterio
  from rasterio._env import driver_count
label_desc: Use image node_id 4 for calling a global function with example usage: test_cpl_debug_false(tmpdir) without return types