title: Send notification to only one user using his Firebase Auth id
body: <p>I want to send notification using firebase to only one user and his token is saved in firebase batabase. I will retrieve data this token from database but how can send notification to that user. </p>
  
  <pre><code> refForLeaveReq.addValueEventListener(new ValueEventListener() {
          @Override
          public void onDataChange(DataSnapshot dataSnapshot) {
              // Here i want to send Notification to only one user and his id is 7bvftaksdyej2383dnd4jdbek4dksb3kdh
          }
  
          @Override
          public void onCancelled(DatabaseError databaseError) {
  
          }
      });
  </code></pre>
  
  <p>If someone know other technique to send notification rather than firebase he/she can tell me.</p>