code: public void packSymbols(int first, int end) {
          int src;
          int dest;
          boolean touched;
  
          dest = first;
          for (src = first; src < end; src++) {
              touched = renameSymbol(src, dest);
              if (touched) {
                  dest++;
              } else {
                  // src not found; dest stays unused
              }
          }
      }
docs: pack helper symbols
  @param end = last + 1