add: }
context: Scheme_Hash_Table *scheme_setup_datum_graph(Scheme_Object *o, void *for_print){  Scheme_Hash_Table *ht;  int counter = 1;  ht = scheme_make_hash_table(SCHEME_hash_ptr);  setup_graph_table(o, ht, &counter, (PrintParams *)for_print);  if (counter > 1)    return ht;  else    return NULL;}