const animals = ['pigs', 'goats', 'sheep'];
console.error('***** adding a single element (cows) at last *****');
const count = animals.push('cows');
console.log(animals); // output: Array ["pigs", "goats", "sheep", "cows"]
console.error('***** adding [chickens, cats, dogs] at last *****');
animals.push('chickens', 'cats', 'dogs');
console.log(animals); // output: Array ["pigs", "goats", "sheep", "cows", "chickens", "cats", "dogs"]