title: Tweepy mentions_timeline returns an empty list
body: <p>I just started to make a Twitter Api. Normally I don't have a Twitter account, for this api I created one. I Tweeted 4 times, including some mentions. But when I use <code>mentions_timeline</code> like this;</p>
  
  <pre><code>my_mentions = api.mentions_timeline()
  #print(my_mentions)
  #output: []
  </code></pre>
  
  <p>After then I do a for loop on my_mentions with parameters <code>text</code>, <code>screen_name</code> but nothing returned.</p>
  
  <p>What I'm doing wrong here? Why it's an empty list since I mentioned some people in the tweets + how can I search mentions for another user? Is there a parameter in <code>mentions_timeline()</code> object like <code>screen_name</code> or <code>id</code> ? </p>