code: public DeweyNumber addStage() {
  		int[] newDeweyNumber = Arrays.copyOf(deweyNumber, deweyNumber.length + 1);
  
  		return new DeweyNumber(newDeweyNumber);
  	}
docs: Creates a new dewey number from this such that a 0 is appended as new last digit.
  
  @return A new dewey number which contains this as a prefix and has 0 as last digit