title: How to make end time of 1st row as start time of 2nd row in python
body: <p>How can I make end time of 1st row as start time of 2nd row (I intend to add some value in seconds to the start time in every row and the end time of the very same row needs to be start time of next row).</p>
  
  <p>For example,</p>
  
  <pre><code>start-time|time_to_add|endtime
  
  10:00:00  |30 secs   |10:00:30
  
  10:00:30  | 15 secs  | 10:00:45
  
  10:00:45  | 10 secs  | 10:00:55
  </code></pre>
  
  <p>Any help would be appreciated.</p>
  
  <p>Thanks</p>
  
  <p><em>edit</em> </p>
  
  <pre><code>starttime  | val_to_add |  endtime
  
  10:30:00   | 30     |   10:30:00 + 0:0:30
  
  10:30:00 + 0:0:30  | 30   | 10:30:00 + 0:0:30 + 0:0:30
  </code></pre>