title: discord.ext.commands.errors.CommandInvokeError: TypeError: ban() got an unexpected keyword argument 'reason'
body: <p>I have seen other bots use the =reason argument in ban() but it doesn't work for me. I want the reason to show up in Discord's server logs (in the ban list) rather than mine. Example code:</p>
  
  <pre><code>@client.command(pass_context=True)
  async def ban(ctx, member: discord.Member, banreason: str):
  await client.ban(member, delete_message_days=7, reason=banreason)
  </code></pre>