title: How to convert elements in a list of list to lowercase?
body: <p>I am trying to convert the elements of a list of list of lowercase. This is what is looks like.</p>
  
  <pre><code>print(dataset)
  [['It', 'went', 'Through', 'my', 'shirt', 'And', 'came', 'out', 'The', 'back', 'and', 'hit', 'the', 'kid', 'behind', 'me', 'in', 'the', 'toe']]
  </code></pre>
  
  <p>I have tried doing this:</p>
  
  <pre><code>for line in dataset:
      rt=[w.lower() for w in line]
  </code></pre>
  
  <p>However this gives me an error saying list object has no attribute lower(). </p>