Update start_stop_counter.py

Author: insolor

examples/start_stop_counter.py

@@ -4,35 +4,35 @@
 
 from async_tkinter_loop import async_mainloop
 
+event = asyncio.Event()
+
 
 async def counter():
     i = 0
     while True:
-        await event.wait()
+        await event.wait()  # pauses if `event` object is cleared, unpauses if it is set
         i += 1
         label.config(text=str(i))
         await asyncio.sleep(1.0)
 
 
-root = tk.Tk()
-
-label = tk.Label(root)
-label.pack()
-
-event = asyncio.Event()
-
-
 def start_stop():
     if event.is_set():
         event.clear()
     else:
         event.set()
 
 
+root = tk.Tk()
+
+label = tk.Label(root)
+label.pack()
+
 tk.Button(root, text="Start/stop", command=start_stop).pack()
 
-# Start background task
+# Create a new asyncio event loop, then run `counter()` as a background task
 event_loop = asyncio.new_event_loop()
 task = event_loop.create_task(counter())
 
+# `event_loop` should be passed to `async_mainloop` in this case, so that it won't create a new event loop
 async_mainloop(root, event_loop)