code: String stringValue( CssFormatter formatter ) {
          String str;
          try {
              formatter.addOutput();
              appendTo( formatter );
          } catch( Exception ex ) {
              throw createException( ex );
          } finally {
              str = formatter.releaseOutput();
          }
          return str;
      }
docs: Get the string value
  
  @param formatter
  the CCS target
  @return the value