title: NLTK not working on iPython
body: <p>I'm working with MacOS, I've installed Python and iPython, but when I type:</p>
  
  <pre><code>import nltk
  </code></pre>
  
  <p>ipython tells me that there is no module named <code>nltk</code>. However, when I type in:</p>
  
  <pre><code>import sys 
  
  import nltk
  </code></pre>
  
  <p>It works perfectly fine. Can someone explain why this isn't working correctly? I'm a newbie to Python so please be gentle. Thanks.</p>