 Complete the following phrase:  Rimsky-Korsakovs editing of works by The Five is significant. It was a practical extension of the collaborative atmosphere of The Five during the 1860s and 1870s, when they heard each others compositions in progress and worked on them together, and was an effort to save works that would otherwise either have languished unheard or become lost entirely. This work included the completion of Alexander Borodins opera Prince Igor, which Rimsky-Korsakov undertook with the help of Glazunov after Borodins death, and the orchestration of passages from César Cuis William Ratcliff for its first production in 1869. He also completely orchestrated the opera 