title: Find difference when comparing lists of sets
body: <p>How do I find the difference of two lists that contains sets?</p>
  
  <pre><code>List 1:
      [{0, 1, 3, 9}, {2, 5, 6}, {8, 4}]
  List 2:
      [{6, 7, 8, 9}]
  </code></pre>
  
  <p><strong>Result should be:</strong></p>
  
  <pre><code>[{7}]
  </code></pre>