code: def create_ctth_variables(nc_file, var_name):
      """Create a CRE variable."""
      var = nc_file.create_variable(
          var_name, ("ny", "nx"), np.uint16, chunks=(256, 256)
      )
      var[:] = CRE_ARRAY
      var.attrs["scale_factor"] = COT_SCALE
      var.attrs["add_offset"] = COT_OFFSET
      var.attrs["_FillValue"] = 65535
  
imports: import h5netcdf
  import numpy
  import pytest
  import xarray
  from satpy.readers.nwcsaf_nc import NcNWCSAF, read_nwcsaf_time
label_desc: Use image node_id 12 for calling a global function with example usage: create_ctth_variables(nc_file, var_name) without return types