我有以下情况：
TMyFormClass = class of TMyForm
function IsMyClass(AClass: TFormClass);
begin
Result := AClass is TMyForm // Operator not applicable to this operand type
Result := AClass is TMyFormClass // Operator not applicable to this operand type
end;
两行都没有建立，错误是运算符不适用于此操作数类型。
我该如何进行比较？