title: How do you replace one push notification with another on the receiving device?
body: <p>I'm trying to replicate how WhatsApp signals the callee's device about an incoming call when the caller starts a call to a user who has this WhatsApp closed. According to the lock screen, the call receiver's device seems to be repeatedly receiving push notification with an interval of approximately 1 second, saying "Call from UserName". But most notably, the notifications do not pile up. It appears that every notification about an incoming call is replaced by the next such notification. And when the caller drops the call, the last incoming-call notification on the callee end is replaced by "Missed call" notification.</p>
  
  <p>How can I achieve push notification replacement/deletion in this way?</p>