DECLARE_SCHEME_CALLBACK (print, (SCM));
DECLARE_SCHEME_CALLBACK (calc_direction, (SCM));
DECLARE_SCHEME_CALLBACK (calc_positioning_done, (SCM));
DECLARE_SCHEME_CALLBACK (print, (SCM));
DECLARE_SCHEME_CALLBACK (calc_direction, (SCM));
DECLARE_SCHEME_CALLBACK (calc_positioning_done, (SCM));