code: public void
  jump(int index) {
  	if (index >= byteBuffer.capacity()) {
  		throw new IllegalArgumentException("cannot jump past " +
  						   "end of input");
  	}
  	byteBuffer.position(index);
  	byteBuffer.limit(byteBuffer.capacity());
  }
docs: Resets the current position of the input stream to the specified index,
  and clears the active region.
  @param index The position to continue parsing at.
  @throws IllegalArgumentException The index is not within the input.