title: How can I add mpl_toolkits.mplot3d to matplotlib
body: <p>I want to create a 3d figures using matplotlib. The examples I found start with:</p>
  
  <pre><code>from mpl_toolkits.mplot3d import axes3d
  </code></pre>
  
  <p>But mpl_toolkits.mplot3d is unresolved reference.</p>