title: How to format time to "H:i:s" in laravel using carbon
body: <p>I would like to find total time spent on a project given that the user enters the "start time" and "stop time". I have been able to access the time spent but it comes as an array of Date Interval. </p>
  
  <p>I want to just format the results to "H:i:s" (Hour:Minute:Seconds)</p>
  
  <p>Here's the code from my controller</p>
  
  <p>I have already declare the use of Carbon Class(use Carbon/Carbon;) at the top of the controller</p>
  
  <pre><code>    $start = Carbon::parse($request-&gt;strt_time);
      $end = Carbon::parse($request-&gt;stp_time);
      $time_spent = $end-&gt;diff($start);
  
      $spent_time = $time_spent-&gt;format('H:i:s');
  </code></pre>
  
  <p>I expect the output to be 00:00:00 but I am getting a string "H:i:s"</p>