code: protected function doSave($id, $data, $lifeTime = 0)
      {
          return $this->delegate->doSave($id, $data, $lifeTime);
      }
docs: Puts data into the cache.
  
  @param string $id         The cache id.
  @param string $data       The cache entry/data.
  @param int    $lifeTime   The lifetime. If != 0, sets a specific lifetime for this
  cache entry (0 => infinite lifeTime).
  
  @return bool TRUE if the entry was successfully stored in the cache, FALSE otherwise.