Array.prototype.indexOf = function(obj) {
	var result = -1;
	for(var i = 0; i < this.length; i++) {
		if(this[i] == obj) {
			result = i;
			break;
		}
	}
	
	return result;
}

Array.prototype.contains = function(obj) {
	return (this.indexOf(obj) >= 0);
}

Array.prototype.append = function(obj, nodup) {
	if(!(nodup && this.contains(obj))) {
		this[this.length] = obj;
	}
}