title: Cant get user name discord.py
body: <p>I am making a bot for my favorite twitch streamer and medium length story short, I need a profile function for the bot. It works when you don't @ someone in the second argument, but I want people to be able to see another users profile.</p>
  <pre><code>async def profile(ctx, user=None):
    if user:
      user = discord.User.display_name
    else:
      user = ctx.message.author.name
      
    with open('users.json', 'r') as f:
      file = json.load(f)
  
    await ctx.send(f'PP: ``{file[user]}``')
  </code></pre>
  <p>users.json looks like this:
  <a href="https://i.stack.imgur.com/ctFbq.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ctFbq.png" alt="users.json" /></a></p>