Horizontal movement loop

First of all I want to thank you Kirupa for all the wonderful tutorials. I am just learning actionscript, and your site has been able to clarify a number of things for me. With that said my question is this:

In your tutorial you used the following code to create horizontal movement:[AS]onClipEvent(enterFrame) { speed = 10; this._x += speed; }[/AS]

how would you create a continuous loop of this movement (ie. make the movie move horizontally across the screen over and over).

Sorry if this is an insultingly simple question.