title: Convert list into list of lists
body: <p>I want to convert list into list of list. Example:</p>
  
  <pre><code>my_list = ['banana', 'mango', 'apple']
  </code></pre>
  
  <p>I want:</p>
  
  <pre><code>my_list = [['banana'], ['mango'], ['apple']]
  </code></pre>
  
  <p>I tried:</p>
  
  <pre><code>list(list(my_list))
  </code></pre>