Abstract, unambiguous nothingness in Python

void.py

class Void(object):
    """A placeholder object which never equals itself and always evaluates to False in
    conditions.

    This is useful when you want an abstract, unambiguous way to delineate a value as
    being "not-set".
    
    Ideally, you would subclass this in your context to create a "personal" void class
    no one would ever use besides you. For example:

        class __MyVoid(Void):
            pass
    """
    __eq__ = lambda self, _: False
    __ne__ = lambda self, _: True
    __nonzero__ = lambda self: False
    __repr__ = lambda self: '<Void>'

Ironically, Python does not have a truly abstract, unambiguous type to communicate "nothingness" or "value-not-set." Oft-times Python coders will use ad-hoc sentinel values/types to communicate "not-set." Examples include None or (). However, these sentinels are not abstract: they cannot be used in abstract code because they could feasibly be candidate values in an implementation.