__cmp__.py

class Something:
    #
    # ...
    # class definition
    # ...
    #

    @property
    def sort_value(self):
        return self.some_important_variable

    def __lt__(self, other):
        return self.sort_value <  other.sort_value
    def __le__(self, other):
        return self.sort_value <= other.sort_value
    def __eq__(self, other):
        return self.sort_value == other.sort_value
    def __ne__(self, other):
        return self.sort_value <> other.sort_value
    def __gt__(self, other):
        return self.sort_value >  other.sort_value
    def __ge__(self, other):
        return self.sort_value >= other.sort_value