title: Pandas dataframe get next (trading) day in dataframe
body: <p>I have a date given that may or may not be a trading day, and I have a pandas dataframe indexed by trading days that has returns of each trading day.</p>
  
  <p>This is my date</p>
  
  <pre><code>dt_query = datetime.datetime(2006, 12, 31, 16)
  </code></pre>
  
  <p>And I want to do something like this (returns is a pandas dataframe)</p>
  
  <pre><code>returns.ix[pd.Timestamp(dt_query + datetime.timedelta(days = 1))]
  </code></pre>
  
  <p>However, that may not work as one day ahead may or may not be a trading day.  I could make a try block that loops and tries until we find something, but I'm wondering if there's a more elegant way that just uses pandas.</p>