Abstract Interfaces in Python

interface.py

import abc

class Interface(abc.ABC):
    
    __slots__ = ()
    
    @classmethod
    def __subclasshook__(cls, obj):
        if cls is not Interface:
            return NotImplemented
        try:
            return all(callable(getattr(obj, method)
                       for method in cls.__abstractmethods__)
        except AttributeError:
           return False

                       
# Example
# Don't need to explicitly implement __subclasshook__
                       
class Iterator(Interface):
    
    @abc.abstractmethod
    def __iter__(self):
        pass
    
    @abc.abstractmethod
    def next(self):
        pass
       
                       
it = iter(list())  # don't need to explicitly subclass
print(isinstance(it, Iterator))