Least and greatest objects in python

least_greatest.py

class _Singleton(type):
    _instances = {}

    def __call__(cls, *pargs, **kwargs):
        mcls = cls.__class__
        if cls not in mcls._instances:
            mcls._instances[cls] = super().__call__(*pargs, **kwargs)
        return mcls._instances[cls]


class Least(metaclass=_Singleton):
    """
    The type of objects that are smaller than the others. It is used to sort
    the elements of different types, replacing the incomparable types.

    >>> sorted(
    ...     [1, 2, 3, None, 3, 2, 1, 4, 5, None, 6],
    ...     key=lambda num: num if isinstance(num, (int, float)) else Least()
    ... )
    [None, None, 1, 1, 2, 2, 3, 3, 4, 5, 6]

    """
    def __lt__(self, other):
        return True

    def __gt__(self, other):
        return not self.__lt__(other)


class Greatest(metaclass=_Singleton):
    """
    The type of objects that are greater than the others. It is used to sort
    the elements of different types, replacing the incomparable types.

    >>> sorted(
    ...     [1, 2, 3, None, 3, 2, 1, 4, 5, None, 6],
    ...     key=lambda num: num if isinstance(num, (int, float)) else Greatest()
    ... )
    [1, 1, 2, 2, 3, 3, 4, 5, 6, None, None]

    """
    def __gt__(self, other):
        return True

    def __lt__(self, other):
        return not self.__gt__(other)

Можно переделать в Singleton.

В любом случае нужно сделать, чтобы все экземпляры были равны между собой.