code: public String getNextMaskedLine() {
  		if (!isNextLine()) {
  			return null;
  		}
  		StringBuilder str = new StringBuilder();
  		int tagWidth = getTagWidth(nextLine);
  		for (int i = 0; i < tagWidth; ++i) {
  			str.append(" ");
  		}
  		if (nextLine.length() > tagWidth) {
  			str.append(nextLine.substring(tagWidth));
  		}
  		return str.toString();
  	}
docs: Return next line with tag masked with whitespace.