Merge pull request #4374 from mlucool/patch-1

Improve comms.rst example

Author: takluyver

docs/source/comms.rst

@@ -65,16 +65,17 @@ containing Javascript to connect to it.
 
 .. code-block:: python
 
-    def target_func(comm, msg):
+    def target_func(comm, open_msg):
         # comm is the kernel Comm instance
         # msg is the comm_open message
 
         # Register handler for later messages
         @comm.on_msg
         def _recv(msg):
             # Use msg['content']['data'] for the data in the message
+            comm.send({'echo': msg['content']['data']})
 
-        # Send data to the frontend
+        # Send data to the frontend on creation
         comm.send({'foo': 5})
 
     get_ipython().kernel.comm_manager.register_target('my_comm_target', target_func)
@@ -87,8 +88,7 @@ And then open the comm from the frontend:
 
 .. code-block:: javascript
 
-    comm = Jupyter.notebook.kernel.comm_manager.new_comm('my_comm_target',
-                                                         {'foo': 6})
+    const comm = Jupyter.notebook.kernel.comm_manager.new_comm('my_comm_target', {'foo': 6})
     // Send data
     comm.send({'foo': 7})