pep 525: Make shutdown_asyncgens a coroutine

pep-0525.txt

@@ -267,7 +267,7 @@ generators to be GCed.
 
 To make sure that asyncio programs can finalize all scheduled
 asynchronous generators reliably, we propose to add a new event loop
-method ``loop.shutdown_asyncgens(*, timeout=30)``.  The method will
+coroutine method ``loop.shutdown_asyncgens()``.  The method will
 schedule all currently open asynchronous generators to close with an
 ``aclose()`` call.
 
@@ -277,13 +277,12 @@ for the first time.  The idea is that after requesting all asynchronous
 generators to be shutdown, the program should not execute code that
 iterates over new asynchronous generators.
 
-An example of how ``shutdown_asyncgens`` should be used::
+An example of how ``shutdown_asyncgens`` coroutine should be used::
 
     try:
         loop.run_forever()
-        # or loop.run_until_complete(...)
+        loop.run_until_complete(loop.shutdown_asyncgens())
     finally:
-        loop.shutdown_asyncgens()
         loop.close()