code: def tiffs(tmpdir):
      with rasterio.open("tests/data/RGB.byte.tif") as src:
          profile = src.profile
  
          shadowed_profile = profile.copy()
          shadowed_profile["count"] = 4
          with rasterio.open(
              str(tmpdir.join("shadowed.tif")), "w", **shadowed_profile
          ) as dst:
              for i, band in enumerate(src.read(masked=False), 1):
                  dst.write(band, i)
              dst.write(band, 4)
  
          del profile["nodata"]
          with rasterio.open(
              str(tmpdir.join("no-nodata.tif")), "w", **profile
          ) as dst:
              dst.write(src.read(masked=False))
  
          with rasterio.open(
              str(tmpdir.join("sidecar-masked.tif")), "w", **profile
          ) as dst:
              dst.write(src.read(masked=False))
              mask = np.zeros(src.shape, dtype="uint8")
              dst.write_mask(mask)
  
      return tmpdir
  
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 1 for calling a global function with example usage: tiffs(tmpdir) and returns: tmpdir