SOURCE

var mult = function(){
		 	var a = 1;
		 	for(var i=0,l = arguments.length;i<l;i++){
		 		a = a*arguments[i]
		 	}
		 		return a;
		 }
		 var plus = function(){
		 	var a= 0;
		 	for(var i=0,l = arguments.length;i<l;i++){
		 		a = a + arguments[i];
		 	}
		 	return a;
		 }

		 var createProxyFactory = function(fn){
		 	var cache = {};
		 	return function(){
		 		var args = Array.prototype.join.call(arguments,',');
		 		if(args in cache){
		 			return cache[args]
		 		}
		 		return cache[args] = fn.apply(this,arguments)
		 	}
		 }

		 var proxyMult = createProxyFactory(mult),
		 proxyPlus = createProxyFactory(plus);
		 console.log(proxyMult(1,2,3,4))
		 console.log(proxyPlus(6,12,7,2))