title: Print not showing in ipython notebook
body: <p>I am using <code>ipython</code> notebook (<a href="http://ipython.org/notebook.html" rel="noreferrer">http://ipython.org/notebook.html</a>) to do a demo and it seems like the print function is not working:</p>
  
  <p><img src="https://i.stack.imgur.com/10NA4.png" alt="enter image description here"></p>
  
  <p>The commands in the above picture are rewritten here for clarity.</p>
  
  <pre><code>In [1]: 'hello world'
  Out [1]: 'hello world'
  
  In [2]: print 'hello world'
  </code></pre>
  
  <p>In short, there's no print output from the <code>[2]</code>.</p>
  
  <p>Does anyone know whether it's a known bug? And does anyone know how to fix it?</p>