title: Appending to a list in a dictionary
body: <p>I've been attempting to add a value to the end of a list inside a dictionary using a different dictionary. The assignment is a little more complicated, so I have simplified the problem down to these three lines, but keep getting None as a result.</p>
  
  <pre><code>finley = {'a':0, 'b':2, 'c':[41,51,61]}
  crazy_sauce = {'d':3}
  print finley['c'].append(crazy_sauce['d'])
  </code></pre>