Fix type errors in all examples

examples/background_task_asyncio.py

@@ -3,6 +3,9 @@ import asyncio
 
 
 class MyClient(discord.Client):
+    # Suppress error on the User attribute being None since it fills up later
+    user: discord.ClientUser
+
     def __init__(self, *args, **kwargs):
         super().__init__(*args, **kwargs)
 
@@ -18,9 +21,13 @@ class MyClient(discord.Client):
         await self.wait_until_ready()
         counter = 0
         channel = self.get_channel(1234567)  # channel ID goes here
+
+        # Tell the type checker that this is a messageable channel
+        assert isinstance(channel, discord.abc.Messageable)
+
         while not self.is_closed():
             counter += 1
-            await channel.send(counter)
+            await channel.send(str(counter))
             await asyncio.sleep(60)  # task runs every 60 seconds