code: def map_node(s: Node, sk_s: URIRef, gin: Graph, gout: Graph) -> None:
      
      for p, o in gin.predicate_objects(s):
          if not isinstance(o, BNode):
              gout.add((sk_s, p, o))
          else:
              sk_o = subj_pred_idx_to_uri(sk_s, p, gin.value(o, FHIR.index))
              gout.add((sk_s, p, sk_o))
              map_node(o, sk_o, gin, gout)
docs: Transform the BNode whose subject is s into its equivalent, replacing s with its 'skolemized' equivalent
      :param s: Actual subject
      :param sk_s: Equivalent URI of subject in output graph
      :param gin: Input graph
      :param gout: Output graph