code: protected function start($time = 1)
      {
          if (file_exists($this->file)) {
              if (time() - $time < filemtime($this->file)) {
                  die(readfile($this->file));
              }
              return $this->delete();
          }
  
          touch($this->file);
      }
docs: Cache start
  
  @param int $time
  
  @return mixed