Should I use abstract classes?

Question

I have read that this is the best way to implement an abstract class in Python (as opposed to the abc module):

class Animal(object):
    def speak(self):
        raise NotImplementedError()

class Duck(Animal):
    def speak(self):
        print("quack")

class Cat(Animal):
    def speak(self):
        print("meow")

However, should I use abstract classes? Should I or should I not just use one less class like so:

class Duck(object):
    def speak(self):
        print("quack")

class Cat(Animal):
    def speak(self):
        print("meow")

Answer 1

There's no one answer to this problem. Do you need a consistent interface between types of Animal? Then some kind of abstract base class would be useful, whether it's from abc or not. If Duck is the only Animal, or there are few similarities between them, then there's rarely much point.