code: def test_update_nodatavals_none(data):
      """GDAL 2.1 does support un-setting nodata values."""
      tiffname = str(data.join("RGB.byte.tif"))
      with rasterio.open(tiffname, "r+") as f:
          f.nodata = None
      with rasterio.open(tiffname) as f:
          assert f.nodatavals == (None, None, None)
  
file_path: rasterio/tests/test_update.py
imports: import subprocess
  import re
  import affine
  import numpy
  import pytest
  import rasterio
label_desc: Use image node_id 6 for calling a global function with example usage: test_update_nodatavals_none(data) without return types