docs: def normalize_object_slot(self, value=_nothing, prop=None, obj=None):
          """This hook wraps ``normalize_slot``, and performs clean-ups which
          require access to the object the slot is in as well as the value.
          """
          if value is not _nothing and hasattr(prop, "compare_as"):
              method, nargs = getattr(prop, "compare_as_info", (False, 1))
              args = []
              if method:
                  args.append(obj)
              if nargs:
                  args.append(value)
              value = prop.compare_as(*args)
          return self.normalize_slot(value, prop)