code: def test_masking_sidecar_mask(tiffs):
      # If the dataset has a .msk sidecar mask band file, all masks will
      # be derived from that file.
      with rasterio.open(str(tiffs.join("sidecar-masked.tif"))) as src:
          for flags in src.mask_flag_enums:
              assert MaskFlags.per_dataset in flags
              assert MaskFlags.alpha not in flags
              assert MaskFlags.nodata not in flags
          rgb = src.read(masked=True)
          assert rgb.mask.all()
          r = src.read(1, masked=True)
          assert r.mask.all()
          masks = src.read_masks()
          assert not masks.any()
  
file_path: rasterio/tests/test_band_masks.py
imports: import numpy
  import pytest
  import rasterio
  from rasterio.enums import MaskFlags
  from rasterio.errors import NodataShadowWarning
label_desc: Use image node_id 12 for calling a global function with example usage: test_masking_sidecar_mask(tiffs) without return types