title: My function returns None, Python 3
body: <p>I am not too sure why this returns None, it worked perfectly before I tried putting it into a function. It is supposed to return a list of words that are between 6 and 9 characters long. </p>
  
  <pre><code>def level_list(minn, maxx):
      for words in word_list:
          if len(words) &gt;= minn and len(words) &lt;= maxx:
              return level_words.append(words)
  
  print(level_list(6, 9))
  </code></pre>