const items = ['Pencil', 'Notebook', 'yo-yo', 'Gum']; function firstItem(arr, cb) { // firstItem passes the first item of the given array to the callback function. return cb(arr[0]); } function getLength(arr, cb) { // getLength passes the length of the array into the callback. return cb(arr.length); } function last(arr, cb) { // last passes the last item of the array into the callback. return cb(arr[arr.length-1]); } function sumNums(x, y, cb) { // sumNums adds two numbers (x, y) and passes the result to the callback. return cb(x+y); } function multiplyNums(x, y, cb) { // multiplyNums multiplies two numbers and passes the result to the callback. return cb(x*y); } function contains(item, list, cb) { // contains checks if an item is present inside of the given array/list. // Pass true to the callback if it is, otherwise pass false. return cb(list.includes(item)); } /* STRETCH PROBLEM */ function removeDuplicates(array, cb) { // removeDuplicates removes all duplicate values from the given array. // Pass the duplicate free array to the callback function. // Do not mutate the original array. const noDuplicates = []; for(num in array){ if (noDuplicates.includes(array[num]) === false){ noDuplicates.push(array[num]); } } return cb(noDuplicates); }