Pending removal in Python 3.21
------------------------------

* :mod:`ast`:

  * Classes ``slice``, ``Index``, ``ExtSlice``, ``Suite``, ``Param``,
    ``AugLoad`` and ``AugStore``, will be removed in Python 3.21. These types
    are not generated by the parser or accepted by the code generator.
  * The ``dims`` property of ``ast.Tuple`` will be removed in Python 3.21. Use
    the ``ast.Tuple.elts`` property instead.
