Issue #16485: Fix file descriptor not being closed if file header patching fails on closing of aifc file.

The code isn't exactly equivalent because a classmethod would
only make sense inside a chain class, and it would need "cls"
as a first argument, and it would need to return an instance
of "chain" rather than a generator.

The updated example drops the @classmethod decorator so that
it can be used standalone:  list(from_iterable(['abc', 'def']))
This should be communicate what from_iterable does.

This patch also provides a simple way to share tests going forward
between test_int and test_long.

When converting REG_DWORD registry values into Python, the conversion
needs to be made from an *unsigned* long (k instead of i) to match the
DWORD type.

This fixes a ValueError seen in winreg.SetValueEx when passed long
winreg.REG_DWORD values that should be supported by the underlying API.

Mostly about symlinks and str/unicode behavior.

Patch by Serhiy Storchaka.

This adds to the work done for issue #15990 (i.e. f44b8d69e5fc and the
commits referenced there).

Fix line buffering of socket._fileobject

#16666: document default values for socket.getaddrinfo in the text to clarify that it doesn't accept keyword args.

Patch Serhiy Storchaka.