title: How can I get an argument from error for discord.py?
body: <p>I want to get an argument like in the image below:</p>
  
  <p><a href="https://i.stack.imgur.com/4yyWL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4yyWL.png" alt="enter image description here"></a></p>
  
  <p>My code:</p>
  
  <pre><code>class Admin(commands.Cog):
      def __init__(self, bot):
          self.bot = bot
  
      @commands.command()
      async def purge(self, ctx, amount: int):
          await ctx.channel.purge(limit=amount+1)
  
      @purge.error
      async def purge_error(self, ctx, error):
          if isinstance(error, commands.MissingRequiredArgument):
              await ctx.send('Please enter a number.')
          elif isinstance(error, commands.BadArgument):
              await ctx.send('This is not a number.')
  </code></pre>
  
  <p>How can I do it?</p>