closure and proto problem

calc.js

function calc(value) {
    const args = [value];
    const recursiveCalc = function(value) {
        if (args.length < 2) {
            args.push(value);
        }
        return recursiveCalc;
    }
    recursiveCalc.__proto__.add = () => args[0] + args[1]
    recursiveCalc.__proto__.substract = () => args[0] - args[1]
    return recursiveCalc;
}

calc(x)(y).add() //output (x + y)
calc(x)(y).substract() //output (x - y)

sum.js

function sum(x) {
    var plus = x;
    var recursiveSum = function(x) {
        plus += x;
        return recursiveSum;
    }
    recursiveSum.__proto__.done = function() { return plus; }
    return recursiveSum;
}

var s = sum(1)(2)(3)(4)(5)(6);
console.log(s.done())