function sum(arr) {
//let sum = 0;
//let len = arr.length;
//for(let i=0; i<len; i++){
// sum += arr[i]
//}
//return sum;
return arr.reduce((prev, cur)=>prev+cur)
}
function sum(arr) {
//let sum = 0;
//let len = arr.length;
//for(let i=0; i<len; i++){
// sum += arr[i]
//}
//return sum;
return arr.reduce((prev, cur)=>prev+cur)
}