title: From tuples to multiple columns in pandas
body: <p>How do I convert this dataframe</p>
  
  <pre>
                                            location  value                       
  0                   (Richmond, Virginia, nan, USA)    100                       
  1              (New York City, New York, nan, USA)    200                       
  
  </pre>
  
  <p>to this:</p>
  
  <pre>
      city            state       region    country   value
  0   Richmond        Virginia    nan       USA       100
  1   New York City   New York    nan       USA       200
  
  </pre>
  
  <p>Note that the <code>location</code> column in the first dataframe contains tuples. I want to create four columns out of the <code>location</code> column.</p>