code: def complement(self, *args):
          '''Returns the difference of the union of all values and the union of the values in *args.
          '''
          universe = self.union()
          to_diff = self.union(*args)
          return universe.difference(to_difff complement(self, *args):
          '''Returns the difference of the union of all values and the union of the values in *args.
          '''
          universe = self.union()
          to_diff = self.union(*args)
          return universe.difference(to_diff)
docs: Returns the difference of the union of all values and the union of the values in *args.