DECLARE_SCHEME_CALLBACK (brew_chord_slur, (SCM));
DECLARE_SCHEME_CALLBACK (width, (SCM));
DECLARE_SCHEME_CALLBACK (pure_height, (SCM, SCM, SCM));
DECLARE_SCHEME_CALLBACK (brew_chord_slur, (SCM));
DECLARE_SCHEME_CALLBACK (width, (SCM));
DECLARE_SCHEME_CALLBACK (pure_height, (SCM, SCM, SCM));