code: public static String unescapeString(String escapedString) {
          Matcher match = escapeSequence.matcher(escapedString);
          StringBuffer output = new StringBuffer();
          while(match.find()) {
              match.appendReplacement(output, substitution(match.group()));
          }
          match.appendTail(output);
          return output.toString();
      }
docs: Takes an escaped string and returns the unescaped version
  
  @param escapedString the original string
  @return the unescaped string