code: def test_mask_flags_sidecar(tiffs):
      filename = str(tiffs.join("sidecar-masked.tif"))
      with rasterio.open(filename) as src:
          for flags in src.mask_flag_enums:
              assert MaskFlags.nodata not in flags
              assert MaskFlags.alpha not in flags
              assert MaskFlags.per_dataset in flags
  
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 4 for calling a global function with example usage: test_mask_flags_sidecar(tiffs) without return types