text: export function sumInDogYears(animals) {
      return (animals || [])
          .filter(each => each.type == 'dog')
          .map(each => each.age)
          .reduce((sum, each) => sum + each, 0);
  }
  
  export function sumInHumanYears(animals) {
      return sumInDogYears(animals) * 7;
  }