sdfsdf

add.ts

function add(val: number): typeof add;
function add(): number;

function add(val?: number): number | typeof add {
  if (val === undefined) return 0;
  let sum = val;

  function nextFn(val1: number): typeof nextFn;
  function nextFn(): number;

  function nextFn(val1?: number): number | typeof nextFn {
    if (val1 === undefined) return sum;
    sum += val1;
    return nextFn;
  }
  return nextFn;
}

console.log(add());
console.log(add(1)(2)());

const bar = add(1)()
const foo = add(1)(2)(2)();