public function renderDefault()
 {
     $this->template->genres = $this->genres;
     $this->template->songsWithoutGenre = $this->songsManager->getSongsWithoutGenre();
     /** Song[][] */
     $songs = [];
     foreach ($this->genres as $genre) {
         $songs[$genre->getId()] = $this->songsManager->getSongsByGenreId($genre->getId());
     }
     $this->template->songs = $songs;
 }
 public function renderDefault(string $genre = null)
 {
     $this->template->songs = $this->songsManager->getSongsByGenreId($genre);
     $this->template->currentGenre = $genre;
     $this->template->genres = $this->genresManager->getAllGenres();
 }