Your task is to make a function that can take any non-negative integer as a argument and return it with its digits in descending order. Essentially, rearrange the digits to create the highest possible number.
Examples: Input: 21445 Output: 54421
Input: 145263 Output: 654321
Input: 1254859723 Output: 9875543221
function descendingOrder(n){
return parseInt(n.toString().split('').sort().reverse().join(''), 10);
}