void loop()
   if button_is_pressed
      if !press_in_progress
         press_in_progress = true
         start = millis()
   else
      if press_in_progress //Button has been released
         elapsed = millis() - start
         press_in_progress = false
         if elapsed > long_press_threshold
            long_press_function()
         else
            short_press_function()