DECLARE_SCHEME_CALLBACK (dim_callback, (SCM smob, SCM axis));
DECLARE_SCHEME_CALLBACK (print, (SCM ));
DECLARE_SCHEME_CALLBACK (height, (SCM,SCM));
DECLARE_SCHEME_CALLBACK (dim_callback, (SCM smob, SCM axis));
DECLARE_SCHEME_CALLBACK (print, (SCM ));
DECLARE_SCHEME_CALLBACK (height, (SCM,SCM));