How to mention user in slack.client : <p>This might be a simple question, but I can not get it work.</p>

<p>I am using Slack Python Api to mention a user in a channel, and I am referring to the document here, <a href="https://api.slack.com/methods/chat.postMessage" rel="noreferrer">https://api.slack.com/methods/chat.postMessage</a>, and my code is simple as,</p>

<pre><code>from slackclient import SlackClient
sc = SlackClient(token)
message = sc.api_call(
  'chat.postMessage',
  channel='#channelname',
  text='This is a test.'
  )
</code></pre>

<p>This will send a message to the channel, but I can not find any option to mention users. And I tried to put <code>@someone</code> inside the message such as</p>

<pre><code> text='@someone This is a test.'
</code></pre>

<p>The message will be posted but in plain text, but really mentioning someone. 
BTW, I am using a Test Token.(Or maybe this feature is only available for authorized token? )</p>

<p>Is there any option or method to do this?<br>
Thank you in advance.</p>
