script flashing (highlighter)

integer st=0;
default
{
    state_entry()
    {
        llSetTimerEvent(1);
    }

    timer()
    {
        if(st==0)

            llSetAlpha(0.1,ALL_SIDES);
        else
            llSetAlpha(0.5,ALL_SIDES);
        st=1-st;
    }

}