bpo-32314: Implement asyncio.run() (#4852)

Doc/library/asyncio-task.rst

@@ -92,6 +92,24 @@ Coroutines (and tasks) can only run when the event loop is running.
     used in a callback-style code, wrap its result with :func:`ensure_future`.
 
 
+.. function:: asyncio.run(coro, \*, debug=False)
+
+    This function runs the passed coroutine, taking care of
+    managing the asyncio event loop and finalizing asynchronous
+    generators.
+
+    This function cannot be called when another asyncio event loop is
+    running in the same thread.
+
+    If debug is True, the event loop will be run in debug mode.
+
+    This function always creates a new event loop and closes it at
+    the end.  It should be used as a main entry point for asyncio
+    programs, and should ideally only be called once.
+
+    .. versionadded:: 3.7
+
+
 .. _asyncio-hello-world-coroutine:
 
 Example: Hello World coroutine
@@ -104,10 +122,7 @@ Example of coroutine displaying ``"Hello World"``::
     async def hello_world():
         print("Hello World!")
 
-    loop = asyncio.get_event_loop()
-    # Blocking call which returns when the hello_world() coroutine is done
-    loop.run_until_complete(hello_world())
-    loop.close()
+    asyncio.run(hello_world())
 
 .. seealso::
 
@@ -127,7 +142,8 @@ using the :meth:`sleep` function::
     import asyncio
     import datetime
 
-    async def display_date(loop):
+    async def display_date():
+        loop = asyncio.get_running_loop()
         end_time = loop.time() + 5.0
         while True:
             print(datetime.datetime.now())
@@ -135,10 +151,7 @@ using the :meth:`sleep` function::
                 break
             await asyncio.sleep(1)
 
-    loop = asyncio.get_event_loop()
-    # Blocking call which returns when the display_date() coroutine is done
-    loop.run_until_complete(display_date(loop))
-    loop.close()
+    asyncio.run(display_date())
 
 .. seealso::