Modify the Grass$\_$Pokemon subclass so that the attack strength for Grass$\_$Pokemon instances does not change until they reach level $10.$ At level $10$ and up$,$ their attack strength should increase by the attack$\_$boost amount when they are trained.

To test, create an instance of the class with the name as "Bulby". Assign the instance to the variable p$2.$ Create another instance of the Grass$\_$Pokemon class with the name set to "Pika" and assign that instance to the variable p$3.$ Then, use Grass$\_$Pokemon methods to train the p$3$ Grass$\_$Pokemon instance until it reaches at least level $10.$