let cats = ['Bob', 'Willy', 'Mini'];

// pop(): Remove an item from the end of an array
// pop() returns the removed item
cats.pop(); // ['Bob', 'Willy']

// push(): Add items to the end of an array
// push() returns the new array length
cats.push('Mini'); // ['Bob', 'Willy', 'Mini']

// shift(): Remove an item from the beginning of an array
// shift() returns the removed item
cats.shift(); // ['Willy', 'Mini']

// unshift(): Add items to the beginning of an array
// unshift() returns the new array length.
cats.unshift('Puff', 'George'); // ['Puff', 'George', 'Willy', 'Mini']