def _get_cons(self):
            """Return the class used to create instance of this type."""
            if self.__origin__ is None:
                raise TypeError("Cannot get the underlying type of a "
                                "non-specialized Annotated type.")
            tree = self._subs_tree()
            while isinstance(tree, tuple) and tree[0] is Annotated:
                tree = tree[1]
            if isinstance(tree, tuple):
                return tree[0]
            else:
                return tree
Return the class used to create instance of this type.
src/typing_extensions.py