title: set of list of lists in python
body: <p>I am having a <strong>list of lists</strong> :</p>
  
  <pre><code>mat = [[1,2,3],[4,5,6],[1,2,3],[7,8,9],[4,5,6]]
  </code></pre>
  
  <p>and I want to convert into a <strong>set</strong> i.e. remove the repeating lists and creating a new list out of it which will only contain the <strong>unique</strong> lists.</p>
  
  <p>In above case the required answer will be </p>
  
  <pre><code>[[1,2,3],[4,5,6],[7,8,9]]
  </code></pre>
  
  <p>But when I do <code>set(mat)</code>, it gives me error</p>
  
  <blockquote>
    <p>TypeError: unhashable type: 'list'</p>
  </blockquote>
  
  <p>Can you please solve my problem. Thanks in advance!</p>