Get rid of client.loop

Instead, use the asyncio-intended way of implicit loop.

telethon_examples/quart_login.py

@@ -134,12 +134,13 @@ async def main():
 
 
 # By default, `Quart.run` uses `asyncio.run()`, which creates a new asyncio
-# event loop. If we create the `TelegramClient` before, `telethon` will
-# use `asyncio.get_event_loop()`, which is the implicit loop in the main
-# thread. These two loops are different, and it won't work.
+# event loop. Instead, we use `asyncio.run()` manually in order to make this
+# explicit, as the client cannot be "transferred" between loops while
+# connected due to the need to schedule work within an event loop.
 #
-# So, we have to manually pass the same `loop` to both applications to
-# make 100% sure it works and to avoid headaches.
+# In essence one needs to be careful to avoid mixing event loops, but this is
+# simple, as `asyncio.run` is generally only used in the entry-point of the
+# program.
 #
 # To run Quart inside `async def`, we must use `hypercorn.asyncio.serve()`
 # directly.
@@ -149,4 +150,4 @@ async def main():
 # won't have to worry about any of this, but it's still good to be
 # explicit about the event loop.
 if __name__ == '__main__':
-    client.loop.run_until_complete(main())
+    asyncio.run(main())