type validation adjusted

This one is related with this [issue](https://github.com/yiisoft/yii2/issues/3774) .
>You can virtually turn any simple expression into a method

well, no, there are special cases for it. And there are a lot of books describing such cases and other.

>On the contrary, it could make your code more cryptic, because the moment you see a method call, you have to think about what it does and make need to jump to the method implementation to understand it better.

that can lead us to discussion about wrapping everything in one `index.php` file or in functional programming )

>Moreover, when you expose such a method, it becomes part of the class API which users may wonder how he should make use of this method or should he use it at all.

true, however we know principal that object should expose only needed interface, but yet almost none follow it and prefer `public` over `private`.

Well, if you want i can change it back , not for me to decide )