(Y-offset-callbacks . (,Staff_symbol_referencer::callback))
(meta . ((interfaces . (clef-interface staff-symbol-referencer-interface font-interface break-aligned-interface item-interface ))))
))
-
+
+ (ClusterSpannerBeacon
+ . (
+ (molecule-callback . #f)
+ (meta . ((interfaces . (cluster-beacon-interface item-interface))))
+ ))
+
(Cluster
. (
(molecule-callback . ,Cluster::brew_molecule)