#include <Toggle.h>                         // https://github.com/Dlloydev/Toggle

Toggle sw;
const unsigned long longPressDelay = 3000ul;

void setup() {
  Serial.begin(115200);
  sw.begin(3);
  Serial.println("READY");
}

void loop() {
  sw.poll();
  if (sw.pressedFor(longPressDelay)) Serial.println("LONG PRESS");
}