ADD_ACKNOWLEDGER (Beam_collision_engraver, clef);
ADD_ACKNOWLEDGER (Beam_collision_engraver, key_signature);
ADD_ACKNOWLEDGER (Beam_collision_engraver, time_signature);
ADD_ACKNOWLEDGER (Beam_collision_engraver, clef);
ADD_ACKNOWLEDGER (Beam_collision_engraver, key_signature);
ADD_ACKNOWLEDGER (Beam_collision_engraver, time_signature);