function people_with_age_drink(int $old): string {
  switch(true){
    case ($old >= 21):
      return 'drink whisky';
      break;
    case (18 < $old < 21):
      return 'drink beer';
      break;
    case (14 < $old < 18):
      return 'drink coke';
      break;
    case ($old < 14):
      return 'drink toddy';
      break;
  }
}