I think, that I don't understand some basics...

I'm stuck with one misunderstanding: - how can I change the immutable? As long as I receive some tuple for Friends initialisation, how can I add a new connection to it? Or how can I remove a connection out of it? With lists or sets it would be OK. But tuples... I cannot change them! I think that I've missed some elementary thing, regarding class initialisation. Please, help me to clarify.