code: public function moveWatch($from, $to)
      {
          if ($this->watch1 == $from) {
              $this->watch1 = $to;
          } else {
              $this->watch2 = $to;
          }
      }
docs: Moves a watch from one literal to another
  
  @param int $from The previously watched literal
  @param int $to   The literal to be watched now