Add Items to an Array with push() and unshift()

An array's length, like the data types it can contain, is not fixed. Arrays can be defined with a length of any number of elements, and elements can be added or removed over time; in other words, arrays are <dfn>mutable</dfn>. In this challenge, we will look at two methods with which we can programmatically modify an array: `Array.push()` and `Array.unshift()`. Both methods take one or more elements as parameters and add those elements to the array the method is being called on; the `push()` method adds elements to the end of an array, and `unshift()` adds elements to the beginning. Consider the following: ```js let twentyThree = 'XXIII'; let romanNumerals = ['XXI', 'XXII']; romanNumerals.unshift('XIX', 'XX'); ``` `romanNumerals` would have the value `['XIX', 'XX', 'XXI', 'XXII']`. ```js romanNumerals.push(twentyThree); ``` `romanNumerals` would have the value `['XIX', 'XX', 'XXI', 'XXII', 'XXIII']`. Notice that we can also pass variables, which allows us even greater flexibility in dynamically modifying our array's data. # --instructions-- We have defined a function, `mixedNumbers`, which we are passing an array as an argument. Modify the function by using `push()` and `unshift()` to add `'I', 2, 'three'` to the beginning of the array and `7, 'VIII', 9` to the end so that the returned array contains representations of the numbers 1-9 in order.