A little help with my classes program

Question

I'm creating a class to test my knowledge in classes, so I've made a class that contains student names and grades. coding all of that it was easy, but the part I'm stuck on is allowing the user to change the grade of one of the students. a a little help?
https://code.sololearn.com/cTfmswdVT2kC/?ref=app

Answer 1

It is easy :
create a method like check_grade (ex : set_grade) which will change the grade of a person.
In this method you can add constraints