-startGraceSlur = #(make-music 'SlurEvent 'span-direction START 'spanner-id "grace")
-stopGraceSlur = #(make-music 'SlurEvent 'span-direction STOP 'spanner-id "grace")
+startGraceSlur = #(make-music 'SlurEvent 'span-direction START 'spanner-id 'grace)
+stopGraceSlur = #(make-music 'SlurEvent 'span-direction STOP 'spanner-id 'grace)