title: add two lists then sort = None(?)
body: <p>Second list squared each item on list, xs. Running the code below, python gives me 'None'</p>
  
  <pre><code>xs = [12, 10, 32, 3, 66, 17, 42, 99, 20]
  a = [b**2 for b in xs]
  c = (a + xs).sort()
  print(c, end=', ')
  </code></pre>
  
  <p>Same list but different code--</p>
  
  <pre><code>xs = [12, 10, 32, 3, 66, 17, 42, 99, 20]
  a = [b**2 for b in xs]
  c = a + xs
  c.sort()
  print(c, end=', ')
  </code></pre>
  
  <p>...python gives me my list(c), all sorted. I don't get it. Or is there a more pythonic way to do this?</p>
  
  <p>Thanks!</p>