Improve getting started for -both- case (#144)

* Improve getting started for -both- case

* Minor tweaks.

docs/intro.rst

@@ -90,28 +90,26 @@ messages on the same connection.
 
 ::
 
-    async def handler(websocket, path):
+    async def consumer_handler(websocket):
+        while True:
+            message = await websocket.recv()
+            await consumer(message)
+
+    async def producer_handler(websocket):
         while True:
-            listener_task = asyncio.ensure_future(websocket.recv())
-            producer_task = asyncio.ensure_future(producer())
-            done, pending = await asyncio.wait(
-                [listener_task, producer_task],
-                return_when=asyncio.FIRST_COMPLETED)
-
-            if listener_task in done:
-                message = listener_task.result()
-                await consumer(message)
-            else:
-                listener_task.cancel()
-
-            if producer_task in done:
-                message = producer_task.result()
-                await websocket.send(message)
-            else:
-                producer_task.cancel()
-
-(This code looks convoluted. If you know a more straightforward solution,
-please let me know about it!)
+            message = await producer()
+            await websocket.send(message)
+
+    async def handler(websocket, path):
+        consumer_task = asyncio.ensure_future(consumer_handler(websocket))
+        producer_task = asyncio.ensure_future(producer_handler(websocket))
+        done, pending = await asyncio.wait(
+            [consumer_task, producer_task],
+            return_when=asyncio.FIRST_COMPLETED,
+        )
+
+        for task in pending:
+            task.cancel()
 
 Registration
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