title: Discord.py 'VoiceState' object has no attribute 'voice_channel'
body: <p>I use a class structure. I'm writing a Discord bot, for play sound. but I'm faced with a problem.</p>
  
  <p>My <code>music.py</code> file:</p>
  
  <pre class="lang-py prettyprint-override"><code>import discord
  from discord.ext import commands
  
  
  class muzikkomut(commands.Cog):
      def __init__(self, bot):
          self.bot = bot
  
      @commands.command(pass_context=True)
          async def play(self, mesaj):
              kanal = mesaj.message.author.voice.voice_channel
              await self.bot.join_voice_channel(kanal)
  
  
  def setup(bot):
      bot.add_cog(muzikkomut(bot))
  </code></pre>