title: Round time to nearest hour python
body: <p>I was trying to round off time to the nearest hour in python in a dataframe.</p>
  
  <p>Suppose if a timestamp is <code>2017-11-18 0:16</code> it should come as <code>2017-11-18 0:00</code>
  and <code>2017-11-18 1:56</code> should round off as <code>2017-11-18 2:00</code></p>