AS3 isDefinition() function

isDefinition.as

package {
	import flash.utils.describeType;
	//
	// trace( isDefinition(Sprite,"flash.display::Sprite")            ); // true
	// trace( isDefinition(Sprite,"flash.display::InteractiveObject") ); // true
	// trace( isDefinition(Sprite,"flash.events::EventDispatcher")    ); // true
	// trace( isDefinition(Sprite,"flash.events::Event")              ); // false
	//
	public function isDefinition( definition:Class, type:String ):Boolean {
		var info:XML = describeType( definition );
		if( info.@name == type ) {
			return true;
		}
		for each( var item:XML in info.factory.extendsClass ) {
			if( item.@type == type ) {
				return true;
			}
		}
		return false;
	}
}