Berlioz, Gluck, Halevy, Humperdinck, Verdi, Wagner and Weber Arr: Walker . FLUTE DUET. A feast of melodies from the operas of Verdi, Gluck, Berlioz and more - some well-known, some neglected gems - all skilfully arranged with plenty of interest in both parts. Pieces are approximately Grade: 4 - 6 standard.