Casals used to play the "Cant des Ocells" as a tribute to political prisoners under Franco and in hope that Catalonia and Spain would be free of fascism one day. Here it is being played, every evening by a saxophonist in Tarragona to show solidarity with Catalan political prisoners of the neo-Francoist regime today:

https://twitter.com/Apporelly/status/939556451298705408