function(subscribers, value) {
	if(!subscribers) return;
	
	var subs = subscribers.slice();
	for(var i = 0; i < subs.length; i++) {
		if(typeof subs[i] == "function") subs[i](value);
		else if(typeof subs[i].call == "function") subs[i].call(value);
		else throw new TypeError("Observer is not callable.");
	}
}
function(subscribers, value) {
	if(!subscribers) return;
	
	var subs = subscribers.slice();
	for(var i = 0; i < subs.length; i++) {
		if(typeof subs[i] == "function") subs[i](value);
		else if(typeof subs[i].call == "function") subs[i].call(value);
		else throw new TypeError("Observer is not callable.");
	}
}
function ( subscribers , value ) { if ( ! subscribers ) return ; var subs = subscribers . slice ( ) ; for ( var i = 0 ; i < subs . length ; i ++ ) { if ( typeof subs [ i ] == "function" ) subs [ i ] ( value ) ; else if ( typeof subs [ i ] . call == "function" ) subs [ i ] . call ( value ) ; else throw new TypeError ( "Observer is not callable." ) ; } }
notify subscribers (private helper)
notify subscribers ( private helper )