title: Find all users(reply_channels) added in Group (Django channels)
body: <p>I am using Django channels Group to build a chat system and want to fetch all the users in chat room.</p>
  
  <p>Group provide these methods :</p>
  
  <ul>
  <li><code>Group("group_name").add(message.reply_channel)</code></li>
  <li><code>Group("group_name").discard(message.reply_channel)</code></li>
  <li><code>Group("group_name").send({"text": "My group message",})</code></li>
  </ul>
  
  <p>But there is nothing like that I can find all users(reply_channel) in Group.</p>
  
  <p>Thanks</p>