code: public boolean runOnMainThreadAtTime(Runnable r, long uptimeMillis) {
          assert handler != null;
  
          if (!sanityCheck("runOnMainThreadAtTime " + r)) {
              return false;
          }
          return handler.postAtTime(r, uptimeMillis);
      }
docs: Queues a Runnable to be run on the main thread at the time specified by
  {@code uptimeMillis}. The time base is {@link SystemClock#uptimeMillis()
  uptimeMillis()} . A pause in application execution may add an additional
  delay.
  
  @param r
  The Runnable to run on the main thread.
  @param uptimeMillis
  The absolute time at which the Runnable should be run, in
  milliseconds.
  @return Returns {@code true} if the Runnable was successfully placed in
  the Looper's message queue.