private def extendScope(members: List[Member], fs: FieldScope, ms: MethodScope): Unit = members match {
    case mem :: mems => mem match {
      case Field(fieldName, tipe, expr) => {
        fs.get(fieldName) match {
          case Some(FieldSymbol(dt: DataType)) => Report.error(mem.pos, "Field " + fieldName + " is already defined")
          case None => {
            fs + ((fieldName, FieldSymbol(tipe)))
            extendScope(mems, fs, ms)
          }
        }
      }
  
      case Method(methodName, arguments, returnType, expr) => {
        def addArgs(args: List[(String, DataType)], accu: List[DataType]): Unit = args match {
          case arg :: nextArgs => addArgs(nextArgs, accu ::: List(arg._2))
          case Nil => ms + ((methodName, MethodSymbol(accu, returnType)))
        }
        
        ms.get(methodName) match {
          case Some(MethodSymbol(listDt: List[DataType], dt: DataType)) => Report.error(mem.pos, "Method " + methodName + " is already defined")
          case None => {
            addArgs(arguments, Nil)
            extendScope(mems, fs, ms)
          }
        }
      }
    }
  
    case Nil => //exit
  }