| ``_abc`` module is added. It is a speedup module with C implementations for |
| various functions and methods in ``abc``. Creating an ABC subclass and calling |
| ``isinstance`` or ``issubclass`` with an ABC subclass are up to 1.5x faster. |
| In addition, this makes Python start-up up to 10% faster. |
| |
| Note that the new implementation hides internal registry and caches, previously |
| accessible via private attributes ``_abc_registry``, ``_abc_cache``, and |
| ``_abc_negative_cache``. There are three debugging helper methods that can be |
| used instead ``_dump_registry``, ``_abc_registry_clear``, and |
| ``_abc_caches_clear``. |