class Banking(object): ...

class BankingBank1(Banking): ...

class BankingBank2(Banking): ...

def user_action(bb_obj):
    try:
        bb_obj.process_payment('destination_address', 100)
    except NotImplementedError as e:
        print('Cannot process the payment.')


bb2 = BankingBank2(__name__)
user_action(bb2)