SCM_CLASS_PROMISE 3035 src/class.c        CINIT(SCM_CLASS_PROMISE,          "<promise>");
SCM_CLASS_PROMISE 2955 src/extlib.c    SCM_RESULT = (SCM_XTYPEP(obj, SCM_CLASS_PROMISE));
SCM_CLASS_PROMISE 2441 src/gauche.h   #define SCM_PROMISEP(obj)           SCM_XTYPEP(obj, SCM_CLASS_PROMISE)
SCM_CLASS_PROMISE  100 src/promise.c      SCM_SET_CLASS(p, SCM_CLASS_PROMISE);