code: public void jumpahead(int count) {
          if (count < 0) {
              throw new IllegalArgumentException();
          }
          if (buf != null) {
              bufPos += count;
              if (bufPos > buf.length) {
                  throw new IllegalArgumentException();
              }
              if (bufPos == buf.length) {
                  buf = null;
              }
          } else {
              int i = pos.getIndex() + count;
              pos.setIndex(i);
              if (i > text.length()) {
                  throw new IllegalArgumentException();
              }
          }
      }
docs: Advances the position by the given number of 16-bit code units.
  This is useful in conjunction with the lookahead() method.
  @param count the number of 16-bit code units to jump over