What does >> do?
<p>I solved a problem on Project Euler but it took about 4 minutes to run, which is above the recommended time, so I was looking through the different solutions in the forum.  One of them included the symbol &lt;&lt; in a list comprehension.  This is what it looked like</p>

<pre><code>blist.extend([(i &lt;&lt; 1) + 3 for i in range(num) if alist.get(i)])  
</code></pre>

<p>I can't find anywhere what exactly this &lt;&lt; symbol does.
Can someone help me? </p>

<p>Thanks</p>
