AS3 - How to call a function in loaded external swf

At the parent code:

package
{
 import flash.display.Loader;
 import flash.display.Sprite;
 import flash.events.Event;
 import flash.net.URLRequest;

 public class ExampleA extends Sprite
 {
  private var loader:Loader = new Loader();

  public function ExampleA()
  {
   loader.contentLoaderInfo.addEventListener( Event.INIT, onLoaderInit );
   loader.load( new URLRequest( "ExampleB.swf" ) );
  }

  private function onLoaderInit( e:Event ):void
  {
   Object( loader.content ).init( "hello" );
  }
 }
}

at the child code:

package
{
 import flash.display.Sprite;

 public class ExampleB extends Sprite
 {
  public function ExampleB()
  {}

  public function init( param:String ):void
  {
   trace( param ); // hello
  }
 }
}