title: How to set multiple prefixes or make prefix case insensitive in discord.py library?
body: <p>I'm creating a discord bot in python using discord.py library.
  My problem is that I can't have prefix case insensitive.
  Is there any way to make it case insensitive or have multiple prefixes?</p>
  
  <p>I have tried to set the prefix to "" and add the prefix to the commands
  but this will make the bot processing every single message!
  Is there any way?</p>