title: Discord music bot NoneType' object has no attribute 'play'
body: <p>Here is my code :</p>
  <pre><code>voice.play(discord.FFmpegPCMAudio(&quot;song.mp3&quot;), after=lambda e: print(&quot;Song done!&quot;))
  voice.source = discord.PCMVolumeTransformer(voice.source)
  voice.source.volume = 0.07
  </code></pre>
  <p>I got this error:</p>
  <blockquote>
  <p>discord.ext.commands.errors.CommandInvokeError: Command raised an
  exception: AttributeError: 'NoneType' object has no attribute 'play'</p>
  </blockquote>