#!/usr/local/bin/python3
from abc import abstractmethod
from collections import Container, Iterable, Mapping, Sequence, Sized

class Array(Sized, Iterable, Container):
    __slots__ = ()

    @abstractmethod
    def __getitem__(self, key):
        raise KeyError

    @classmethod
    def __subclasshook__(cls, C):
        if cls is Array:
            if any(('__iter__', '__len__', '__contains__') in B.__dict__.keys() for B in C.__mro__):
                return True
        return NotImplemented


class C(object):
  def __len__(self):
    pass

  def __iter__(self):
    pass

  def __contains__(self):
    pass

print(issubclass(C, Array))
print (C.__dict__.keys())