code: def test_channel_is_masked(sgli_vn_file):
      """Test that channels are masked for no-data."""
      handler = HDF5SGLI(sgli_vn_file, {"resolution": "L"}, {})
      did = dict(
          name="VN1",
          resolution=1000,
          polarization=None,
          calibration="counts",
      )
      res = handler.get_dataset(
          did,
          {
              "file_key": "Image_data/Lt_VN01",
              "units": "",
              "standard_name": "",
          },
      )
      assert res.max() == MASK
  
imports: import sys
  from datetime import datetime, timedelta
  import dask
  import h5py
  import numpy
  import pytest
  from satpy.readers.sgli_l1b import HDF5SGLI
label_desc: Use image node_id 11 for calling a global function with example usage: test_channel_is_masked(sgli_vn_file) without return types