If/else doubt - How to say it in script

1

I´ve got a button telling a movieclip to gotoAndPlay a specific frame.

 
on (rollOver) {
 tellTarget ("movieclip") {
  gotoAndPlay ("specificframe")
 }
}

Trouble is that I want the movieclip do play this specific frame only if the MC is courently in frame 4.

something like:
if “movieclip” is in frame 4 gotoAndPlay (“specific frame”)
else do nothing

How do I put this in code?

Could anyone help me please i’d be much obliged.

cheers, Marc