code: def nwcsaf_old_geo_ct_filename(tmp_path_factory):
      """Create a CT file and return the filename."""
      attrs = global_attrs_geo.copy()
      attrs.update(PROJ_KM)
      attrs["time_coverage_start"] = np.array(
          ["2023-01-18T10:39:17Z"], dtype="S20"
      )
      return create_nwcsaf_geo_ct_file(
          tmp_path_factory.mktemp("data-old"), attrs=attrs
      )
  
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 17 for calling a global function with example usage: nwcsaf_old_geo_ct_filename(tmp_path_factory) and returns: create_nwcsaf_geo_ct_file