How to write a static python getitem method?

When an object is indexed, the special method __getitem__ is looked for first in the object's class. A class itself is an object, and the class of a class is usually type. So to override __getitem__ for a class, you can redefine its metaclass (to make it a subclass of type):

class MetaA(type):
    def __getitem__(cls,val):
        return "It works"

class A(object):
    __metaclass__=MetaA
    pass

print(A[0])
# It works

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In Python3 the metaclass is specified this way:

class A(object, metaclass=MetaA):
    pass

Python 3.7 introduced __class_getitem__.

class A:
    def __class_getitem__(cls, key):
        return "It works"

print(A[0])