old_contents: import discord
  from discord.ext import commands
  
  class ErrorFormatter:
      def __init__(self, bot):
          self.bot = bot
  
      @commands.command(name='error', hidden=True)
      async def error_formatter(self, ctx, *, err: str):
          """ Send a nice embed error with a message
  
          Usage:
          class Foo:
              def __init__(self, bot):
                  self.bot = bot
                  self.cmd = bot.get_command('error')
  
          @commands.command()
          async def bar(self, ctx, *, baz):
              # some error happened
              await ctx.invoke(cmd, err='error message here')
          """
          em = discord.Embed(title=':x: Error', color=discord.Color.dark_red(), description=err)
          await ctx.send(embed=em)
  
  
  def setup(bot):
      bot.add_cog(ErrorFormatter(bot))
new_contents: import discord
  from discord.ext import commands
  
  class ErrorFormatter:
      def __init__(self, bot):
          self.bot = bot
  
      @commands.command(name='error', hidden=True)
      async def error_formatter(self, ctx, *, err: str):
          """ Send a nice embed error with a message
  
          Usage:
          class Foo:
              def __init__(self, bot):
                  self.bot = bot
                  self.cmd = bot.get_command('error')
  
          @commands.command()
          async def bar(self, ctx, *, baz):
              # some error happened
              await ctx.invoke(cmd, err='error message here')
          """
          em = discord.Embed(title=':x: Error', color=discord.Color.dark_red(), description=err)
          await ctx.send(embed=em, delete_after=10.0)
  
  
  def setup(bot):
      bot.add_cog(ErrorFormatter(bot))
subject: delete errors after 10 seconds