old_contents: class ComparableMixin:
    def __ne__(self, other):
      return self != other
    def __ge__(self, other):
      return not self<other
    def __le__(self, other):
      return not other<self
  
new_contents: class ComparableMixin:
    def __ne__(self, other):
      return not (self == other)
  
    def __ge__(self, other):
      return not (self < other)
  
    def __le__(self, other):
      return not (other < self)
  
subject: fix ComparableMixin