title: Calculating age from date/time format in python/pandas
body: <p>Looking for a way to calculate age from the following date/time format in python.</p>
  
  <p>eg: 1956-07-01T00:00:00Z </p>
  
  <p>I have written a code to do this by extracting the four characters of the string, convert it to an int and subtract it from 2017 but was looking to see if there is an efficient way to do it.</p>