protected function cacheData(string $key, string $data) : string
    {
        $this->cache[$key] = $data;

        return $data;
    }
protected function cacheData(string $key, string $data) : string
    {
        $this->cache[$key] = $data;

        return $data;
    }
protected function cacheData ( string $ key , string $ data ) : string { $ this -> cache [ $ key ] = $ data ; return $ data ; }
Add an item to the cache

@param string $key
@param string $data
@return string
Add an item to the cache