title: Converting a nested list into list shows unhashable type
body: <p>How to convert a nested list into a separate list?</p>
  <pre><code>rec = [[&quot;A&quot;,[&quot;B&quot;,&quot;C&quot;,&quot;D&quot;]],[&quot;B&quot;,[&quot;D&quot;,&quot;E&quot;,&quot;F&quot;]],[&quot;C&quot;,[&quot;G&quot;,&quot;H&quot;,&quot;I&quot;]]]
  </code></pre>
  <p>Desired output:</p>
  <pre><code>desired_output = [[&quot;A&quot;,&quot;B&quot;,&quot;C&quot;,&quot;D&quot;],[&quot;B&quot;,&quot;D&quot;,&quot;E&quot;,&quot;F&quot;],[&quot;C&quot;,&quot;G&quot;,&quot;H&quot;,&quot;I&quot;]]
  </code></pre>
  <p>I've tried the below code, however, it throws a Type Error: - <strong>unhashable type: 'list'</strong></p>
  <pre><code>data = list(set([tuple(row) for row in rec]))
  </code></pre>
  <p>Any help would be greatly appreciated.</p>
  <p>Thanks in advance.</p>