Scm_UndefinedObjectClass  107 src/class.c    SCM_DEFINE_BUILTIN_CLASS_SIMPLE(Scm_UndefinedObjectClass, NULL);
Scm_UndefinedObjectClass  583 src/gauche.h   SCM_CLASS_DECL(Scm_UndefinedObjectClass);
Scm_UndefinedObjectClass  596 src/gauche.h   #define SCM_CLASS_UNDEFINED_OBJECT (&Scm_UndefinedObjectClass)