title: Operation on numpy array in someone else code
body: <p>I was trying to understand a code written by someone else and i found this:</p>
  
  <pre><code>w &amp;= (n == 2)  
  w |= (n == 3)
  </code></pre>
  
  <p>Where w and n are both numpy arrays.
  I have done some quick research on google but didn't find out what is it if some can tell me, I'd really appreciate that.</p>