I have created a function to sum the values but It does not get the result expected, return 0

```
function ints(t) { this.t=t; }

ints.prototype.sum = function() {
        var sum = 0;
        var value;
        for (var _ in this.t) {
                value = _;
                sum += value;
        }
        return sum;
}

var s = new ints(1, 2, 3, 4, 5);
if (s.sum() !== 15) {
        alert("FAIL: " + s.sum());
}

```

How to fix it using that object? I want not to use a primitive