code: def setup_concept_scheme(rdf, defaultcs):
      
      for conc in rdf.subjects(RDF.type, SKOS.Concept):
          # check concept scheme
          cs = rdf.value(conc, SKOS.inScheme, None, any=True)
          if cs is None:  # need to set inScheme
              rdf.add((conc, SKOS.inScheme, defaultcs))
docs: Make sure all concepts have an inScheme property, using the given
      default concept scheme if necessary.