code: private int readInt() {
      String tag = readWord();
      try {
        int radix = 10;
        if (tag.startsWith("0x") || tag.startsWith("0X")) {
          tag = tag.substring("0x".length());
          radix = 16;
        }
        return Integer.valueOf(tag, radix);
      } catch (Exception e) {
        throw unexpected("expected an integer but was " + tag);
      }
    }
docs: Reads an integer and returns it.