A little interesting side note, Geraldine Farrar's farewell to the Metropolitan Opera in 1922 was in Zazà.
(Double-click the video above or click this link to watch the video on YouTube in HD.)
https://youtu.be/KwWB_Q5-iuIThe story in Zazà concerns the French music hall singer, Zazà, and her affair and subsequent decision to leave her lover, Milio, when she discovers that he is married. This aria which translates to something like "Nevermore Zazà" is Milio's lament over his loss of Zazà.