code: public boolean isCompatibleWith(DeweyNumber other) {
  		if (length() > other.length()) {
  			// prefix case
  			for (int i = 0; i < other.length(); i++) {
  				if (other.deweyNumber[i] != deweyNumber[i]) {
  					return false;
  				}
  			}
  
  			return true;
  		} else if (length() == other.length()) {
  			// check init digits for equality
  			int lastIndex = length() - 1;
  			for (int i = 0; i < lastIndex; i++) {
  				if (other.deweyNumber[i] != deweyNumber[i]) {
  					return false;
  				}
  			}
  
  			// check that the last digit is greater or equal
  			return deweyNumber[lastIndex] >= other.deweyNumber[lastIndex];
  		} else {
  			return false;
  		}
  	}
docs: Checks whether this dewey number is compatible to the other dewey number.
  
  <p>True iff this contains other as a prefix or iff they differ only in the last digit whereas
  the last digit of this is greater than the last digit of other.
  
  @param other The other dewey number to check compatibility against
  @return Whether this dewey number is compatible to the other dewey number