object oriented design – How is inheritance possible with immutability?

The title almost sums it up but let me be example-led and clearer.

Assuming we have a class:

class T:
  def goto(self, value):
    print('go')

And a second inheriting class:

class A(T):
  def __init__(self):
    pass

Now, of course, instances of A can call the goto method.

My question is: Does this break immutability? Do we say: A always inherited T, and T always contained the goto method, so it was not mutated. Or do we say: A precedes T and inherits from T. A is therefore mutated to include the goto method and immutability is broken.

Does that make sense? I tend to think the latter because T could change over time. Therefore, A is not “immutable,” so to speak, by virtue of having inheritance.

So it leaves me wondering: Is inheritance incompatible with immutability?