title: Lowercase all strings in a list by list comprehension
body: <p>I am confused on how my code is not turning all strings into lowercase?    </p>
  
  <pre><code>def set_lowercase(strings):
      """ lower the case 2. """
      return [i.lower() for i in strings]
  
  
  strings = ['Right', 'SAID', 'Fred']
  set_lowercase(strings)
  print(strings)
  </code></pre>