code: private List<Expression> getParamList( CssFormatter formatter ) {
          Expression ex0 = get( 0 ).unpack( formatter );
          if( ex0.getDataType( formatter ) == LIST ) {
              Operation op = ex0.listValue( formatter );
              List<Expression> operants = op.getOperands();
              if( operants.size() == 1 ) {
                  Expression ex0_0 = operants.get( 0 );
                  if( ex0_0.getDataType( formatter ) == LIST ) {
                      return ex0_0.listValue( formatter ).getOperands();
                  }
              }
              return operants;
          }
          List<Expression> result = new ArrayList<Expression>();
          result.add( ex0 );
          return result;
      }
docs: Get for extract and length the first parameter as parameter list.
  
  @param formatter
  current formatter
  @return the list