AppleScript to jump back for some seconds in iTunes

iTunes Jump Back.scpt

tell application "iTunes"
	if player state is playing then
		set jumpInSeconds to 20
		set currTime to get player position
		if currTime < jumpInSeconds then
			set currSkip to 0
		else
			set currSkip to currTime - jumpInSeconds
		end if
		
		set player position to currSkip --skip to new position
	end if
	
end tell