/**
  *
  * @param string $key
  * @param string $str
  * @return bool
  */
 public function append($key, $str)
 {
     $log = LogHandler::getInstance();
     $log->info("[Array cache] Append '{$key}' in L1 Cache");
     $this->_L1Cache[$key] = $this->_L1Cache[$key] . $str;
     return true;
 }