code: @Override
      public void resolve(final ValueStack values) throws Exception
      {
          if (values.size() < getParameterCount())
              throw new Exception("missing operands for " + toString());
          try
          {
              boolean result;
              final Object whoKnowsWhat = values.popStringOrByteArray();
              if (whoKnowsWhat instanceof String)
              {
                  final String target = (String) whoKnowsWhat;
                  result = target.trim().length() == 0;
  
              } else
              {
                  final byte[] target = (byte[]) whoKnowsWhat;
                  result = target == null || target.length == 0;
              }
  
              values.push(new Boolean(result));
  
          } catch (final ParseException e)
          {
              e.fillInStackTrace();
              throw new Exception(toString() + "; " + e.getMessage(), e);
          }
      }
docs: {@inheritDoc}