function partition(array, left, right, compareFn) {
 const pivot = array[Math.floor((right + left) / 2)];
 let l = left;
 let r = right;
 let i = left;
 while (i <= r) {
 if (compareFn(array[i], pivot) === Compare.LESS_THAN) {
 swap(array, i, l);
 i++;
 l++;
 }
 else if (compareFn(array[i], pivot) === Compare.BIGGER_THAN) {
 swap(arr, i, r);
 r--;
 }
 else {
 i++;
 }
 }
 // return [l, r];
 return l;
}