function curry(fn) {
  return function curried(...args) {
    if (args.length >= fn.length) {
      return fn.apply(this, args);
    }
    return (...more) => curried.apply(this, args.concat(more));
  };
}

function add(a, b, c = 10) {
  return a + b + c;
}

const curriedAdd = curry(add);
console.log(`${curriedAdd(1)(2)} ${curriedAdd(1,2,3)} ${curriedAdd(4)(5,6)}`);