Added docs for async_ alias

NEWS

@@ -29,6 +29,8 @@ New features:
   unicode encoding/decoding (:ticket:`#473`).
 - Fixed error caused by missing decoding `~psycopg2.extras.LoggingConnection`
   (:ticket:`#483`).
+- Added ``async_`` as an alias for ``async`` to support Python 3.7 where
+  ``async`` will become a keyword (:ticket:`#495`).
 
 Other changes:
 

doc/src/connection.rst

@@ -706,9 +706,13 @@ The ``connection`` class
 
 
     .. attribute:: async
+                   async_
 
         Read only attribute: 1 if the connection is asynchronous, 0 otherwise.
 
+        .. versionchanged:: 2.7 added the `!async_` alias for Python versions
+            where `!async` is a keyword.
+
 
     .. method:: poll()
 

doc/src/extensions.rst

@@ -29,6 +29,8 @@ introspection etc.
 
     For a complete description of the class, see `connection`.
 
+    .. versionchanged:: 2.7
+        *async_* can be used as alias for *async*.
 
 .. class:: cursor(conn, name=None)
 

doc/src/module.rst

@@ -64,7 +64,8 @@ The module interface respects the standard defined in the |DBAPI|_.
     cursors you can use this parameter instead of subclassing a connection.
 
     Using *async*\=\ `!True` an asynchronous connection will be created: see
-    :ref:`async-support` to know about advantages and limitations.
+    :ref:`async-support` to know about advantages and limitations. *async_* is
+    a valid alias for the Python version where ``async`` is a keyword.
 
     .. versionchanged:: 2.4.3
         any keyword argument is passed to the connection. Previously only the
@@ -76,6 +77,9 @@ The module interface respects the standard defined in the |DBAPI|_.
     .. versionchanged:: 2.7
         both *dsn* and keyword arguments can be specified.
 
+    .. versionchanged:: 2.7
+        added *async_* alias.
+
     .. seealso::
 
         - `~psycopg2.extensions.parse_dsn`