code: @Override
      public void resolve(final ValueStack values) throws Exception
      {
          if (values.size() < getParameterCount())
              throw new Exception("missing operands for " + toString());
  
          try
          {
              final StringBuilder sb = new StringBuilder();
              for (int p = 0; p < getParameterCount(); p++)
              {
                  sb.insert(0, values.popString());
              }
  
              values.push(sb.toString());
          } catch (final ParseException e)
          {
              e.fillInStackTrace();
              throw new Exception(toString() + "; " + e.getMessage(), e);
          }
      }
docs: {@inheritDoc}