Node.js friendly form of the arity checking decorator for javascript

arity_check.js

exports.arity_decorator = function(fun) {
    function wrapped() {
        if(arguments.length != fun.length)
            throw new Error("Y U NO USE RIGHT?!")
        fun.apply(this, arguments)
    }
    return wrapped;
}


exports.foo = function(x, y) {
    console.log('X:' + x)
    console.log('Y:' + y)
}


exports.foo = exports.arity_decorator(exports.foo)

wrap_it.js

var arity_check = require("./arity_check");

var bar = function(z) {
    console.log('Hi. Z:' + z);
}
bar = arity_check.arity_decorator(bar)



arity_check.foo(3,4) // Works

bar(5) // Works

bar(5,6,7) // Throws error