Class method isn't changing the value

Question

Consider a class:

class Whatever: 
    rang = 'itselop'
    def __init__ (self, name):
        self.name = name
        self.suka = name + " " + ' musorskaya'
   
    @classmethod
    def func(cls, attr):
        cls.rang = attr

No error, if this passed in. I write then Whatever.func = 'patskak', expecting that this value shoud overwrite the class variable. But the class variable remains. I thought, this is because strings are immutable; but same thing repeats, when I make 2 integers as the class variable and the class method agrument. Why? Thank you.