magento2 – Magento 2: set the custom price on the product when it is added to the cart

I see some answers about the custom price established in the product when it is added to the cart.

But, I still can not solve my problem. I used the observer for that to set the custom price.

But it is not working.

Can someone please help me solve it?

My code :

public function run ( Magento  Framework  Event  Observer $ observer) {
$ item = $ observer-> getEvent () -> getData (& # 39; quote_item & # 39;);
$ product = $ observer-> getEvent () -> getData (& # 39; product & # 39;);
$ itemProId = $ item-> getProduct () -> getId ();
$ custom_price = $ product-> getPrice () + 10;
$ item-> setCustomPrice ($ custom_price);
$ item-> setOriginalCustomPrice ($ custom_price);
$ item-> getProduct () -> setIsSuperMode (true);
}