Add async(). See https://codereview.appspot.com/9245047/

pep-3156.txt

@@ -260,8 +260,7 @@ methods, and still conform to the other methods.)
 - Basic callbacks: ``call_soon()``, ``call_later()``, ``call_at()``.
 
 - Thread interaction: ``call_soon_threadsafe()``,
-  ``wrap_future()``, ``run_in_executor()``,
-  ``set_default_executor()``.
+  ``run_in_executor()``, ``set_default_executor()``.
 
 - Internet name lookups: ``getaddrinfo()``, ``getnameinfo()``.
 
@@ -903,7 +902,13 @@ However the current PEP strives to have no dependencies beyond Python
 3.3, so changes to ``concurrent.futures.Future`` are off the table for
 now.
 
-There is one public function related to Futures.  It is:
+There are some public functions related to Futures:
+
+- ``async(arg)``.  This takes an argument that is either a coroutine
+  object or a Future (i.e., anything you can use with ``yield from``)
+  and returns a Future.  If the argument is a Future, it is returned
+  unchanged; if it is a coroutine object, it wraps it in a Task
+  (remember that ``Task`` is a subclass of ``Future``).
 
 - ``wrap_future(future)``.  This takes a PEP 3148 Future (i.e., an
   instance of ``concurrent.futures.Future``) and returns a Future