title: Android Resume activity from Stack
body: <p>Hi I have a question, 
     I would like to know which intent flag to use to start an activity that may already exist in the backstack, however it should </p>
  
  <ol>
  <li>Clear all activities on top of it, bringing the current activity to top and</li>
  <li>It should resume the previous activity (NOT start a new instance of it).</li>
  </ol>
  
  <p>Would really appreciate some help on this!</p>