+/*
+ Retrieve all music (starting at HERE), until a music with length L >
+ 0 is found. From the precondition, we know that UNTIL is later than
+ the earliest event. Hence we know
+
+ L >= (UNTIL - HERE)
+
+ so something that comes after this thing with L > 0 happens after
+
+ HERE + L >= HERE + (UNTIL - HERE) = UNTIL
+
+ Hence all events after the one with L>0 are uninteresting, so we
+ ignore them.
+
+*/
+
+SCM
+Sequential_music_iterator::get_music (Moment until)const