Quick start example doesn't respond to ourselves.

README.md

@@ -64,6 +64,10 @@ class MyClient(discord.Client):
         print('------')
 
     async def on_message(self, message):
+        # don't respond to ourselves
+        if message.author == self.user:
+            return
+
         if message.content.startswith('!test'):
             counter = 0
             tmp = await message.channel.send('Calculating messages...')