Class.Occlude = new Class({

	occlude: function(property, element){
		element = $(element || this.element);
		var instance = element.retrieve(property || this.property);
		if (instance && !$defined(this.occluded)){
			this.occluded = instance;
		} else {
			this.occluded = false;
			element.store(property || this.property, this);
		}
		return this.occluded;
	}

});