title: How to combine 2 rows in pandas DataFrame with consecutive timestamp?
body: <p>I have a pandas dataframe like given below</p>
  
  <pre><code>start_time                     end_time   value                                
  2017-01-09 21:49:55 2017-01-09 21:55:41  150.0
  2017-01-09 21:55:41 2017-01-09 21:58:46    4.0
  2017-01-09 22:00:55 2017-01-09 23:13:00  144.0
  </code></pre>
  
  <p>I want </p>
  
  <pre><code>start_time                     end_time   value                                
  2017-01-09 21:49:55 2017-01-09 21:58:46  154.0
  2017-01-09 22:00:55 2017-01-09 23:13:00  144.0
  </code></pre>
  
  <p>As first 2 rows were consecutive events, I joined it into a single row and added their values.
  Any suggestions how can i proceed.</p>