title: Sort column in Pandas DataFrame by specific order
body: <p>Given this DataFrame:</p>
  
  <pre><code>df = pd.DataFrame([['August', 2], ['July', 3], ['Sept', 6]], columns=['A', 'B'])
  </code></pre>
  
  <p>I would like to sort column A in this order: July, August, Sept. Is there some way to use a sort function like "sort_values" but pre-define the sort order by values?</p>