SCM_NEXT_METHOD  2451 src/class.c        ScmNextMethod *nm = SCM_NEXT_METHOD(obj);
SCM_NEXT_METHOD   938 src/vm.c                           ScmNextMethod *n = SCM_NEXT_METHOD(VAL0);
SCM_NEXT_METHOD   988 src/vm.c                           VAL0 = SCM_METHOD(VAL0)->func(SCM_NEXT_METHOD(nm),