title: discord.py "wait_for" a reaction in a command
body: <p>I have a command which sends an embed to a specific channel. The bot then adds a reaction to this message. That works so far.</p>
  <p>Now, when someone clicks on this reaction, I want the bot to respond with a message. But that doesn't work. There is no error, which means that it works in some way, but not like I want.</p>
  <pre><code>@bot.command()
  async def buy(ctx, choice):
      # some code ...
  
      mess1 = await channel.send(embed=embed)
      await mess1.add_reaction('&lt;a:check:674039577882918931&gt;')
  
      def check(reaction, user):
          return reaction.message == mess1 and str(reaction.emoji) == '&lt;a:check:674039577882918931&gt;'
  
      await bot.wait_for('reaction_add', check=check)
      channeldone = bot.get_channel(705836078082424914)
      await channeldone.send('test')
  </code></pre>