This PR implements only the code changes for the PEP; documentation will be added separately.
>>> memoryview(b"x", flags=inspect.BufferFlags.WRITABLE) Traceback (most recent call last): File "<stdin>", line 1, in <module> BufferError: Object is not writable. >>> memoryview(b"x", flags=inspect.BufferFlags.SIMPLE) <memory at 0x103391640>