code: public static void addRetSuccessors(List<Jsr> jsrs, int idx, IntCollection result) {
          int i, max;
  
          max = jsrs.size();
          for (i = 0; i < max; i++) {
              ((Jsr) jsrs.get(i)).addRetSuccessors(idx, result);
          }
      }
docs: idx  index of ret