function setup() {
  let triggers = ScriptApp.getProjectTriggers();
  if (triggers.length > 0) {
    throw new Error('Triggers are already setup.');
  }
  ScriptApp.newTrigger('sync').timeBased().everyHours(1).create();
  // Runs the first sync immediately.
  sync();
}
Sets up the script to run automatically every hour.