/**
* Allows partial application of a function.
*/
Function.prototype.partial = function () {
    var fn = this, args = Array.prototype.slice.call(arguments);
    return function () {
        return fn.apply(this, args.concat(
            Array.prototype.slice.call(arguments)));
    };
};


//examples:

var add = function(x, y) { return x + y; };


var add2 = add.partial(2);
console.log(add2(2)); // shows 4

var add2and2 = add.partial(2,2);
console.log(add2and2()); //shows 4