(issues #21677, #21310).

(issues #21677, #21310).

fix issue #17552: add socket.sendfile() method allowing to send a file over a socket by using high-performance os.sendfile() on UNIX. Patch by Giampaolo Rodola'·

flag has the value 'n'.  Patch by Claudiu Popa.

Initial patch by Olive Kilburn.

must not be empty.

be empty.

Add BaseEventLoop._closed attribute and use it to check if the event loop was
closed or not, instead of checking different attributes in each subclass of
BaseEventLoop.

run_forever() and run_until_complete() methods now raise a RuntimeError('Event loop is
closed') exception if the event loop was closed.

BaseProactorEventLoop.close() now also cancels "accept futures".

while still being written to. With no console, this closed Idle.
Also add missing import and a few other changes.

Patch by Milan Oberkirch.

Printout of keyword args should be in deterministic order in
a mock function call. This will help to write better doctests.

Patch by Saimadhav Heblikar. (2 head merge)

Original patch by Amaury Forgeot d'Arc with a test by bdettmer.