def METHOD_NAME(self,lnum):
    if self.selected is not None:
        self.panel[self.selected].style.backgroundColor = "#FFF"
        self.lnums[self.selected].style.backgroundColor = "#EEE"
    self.selected = lnum
    self.panel[self.selected].style.backgroundColor = "#EEE"
    self.lnums[self.selected].style.backgroundColor = "#DDD"