rearrange = (arr, start, finish) => {
if (start === finish) {
return arr;
}
if (start < finish) {
return arr
.slice(0, start)
.concat(arr.slice(start + 1, finish + 1))
.concat(arr[start])
.concat(arr.slice(finish + 1));
} else {
return arr
.slice(0, finish)
.concat(arr[start])
.concat(arr.slice(finish, start))
.concat(arr.slice(start + 1));
}
}