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")