3AHAT0P

void main() {
  final selector = Selector();
  selector
    .when((value) => value == 3).then((value) => value * 2)
    .whenIsEqual((value) => value == 'QQQ').then((value) { print(value); return null; })
    .fallback((value) => { 'x': 42 });
   
  final selector2 = Selector<int, int>();
  selector2
    .when((value) => value == 3).then((value) => value * 2)

3AHAT0P

const Selector = {
};

interface CaseLine<T, G> {
  condition(value: T): boolean;
  body(value: T): void | G;
}

interface Switcher<T, G> {
  case(caseLine: CaseLine<T, G>): this;

3AHAT0P

const binarySearch = (
  array: number[],
  element: number,
  range: [left: number, right: number] = [0, array.length - 1],
): number => {
  let left = range[0];
  let right = range[1];
  let halfIndex = -1;

  while (left < right) {