title: Remove intersection from two lists in python
body: <p>Given two lists, what is the best way to remove the intersection of the two?  For example, given:</p>
  
  <pre><code>a = [2,2,2,3]
  b = [2,2,5]
  </code></pre>
  
  <p>I want to return:</p>
  
  <pre><code>a = [2,3]
  b = [5]
  </code></pre>