code: def create_ctth_alti_pal_variable_with_fill_value_color(
      nc_file, var_name
  ):
      """Create a palette variable."""
      var = nc_file.create_variable(
          var_name, ("pal_colors_250", "pal_rgb"), np.uint8
      )
      var[:] = PAL_ARRAY
      var.attrs["palette_meanings"] = CTTH_PALETTE_MEANINGS
      var.attrs["fill_value_color"] = [0, 0, 0]
      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 15 for calling a global function with example usage: create_ctth_alti_pal_variable_with_fill_value_color(nc_file, var_name) without return types