rb_add_method_cfunc 1504 class.c            rb_add_method_cfunc(klass, mid, func, argc, METHOD_VISI_PUBLIC);
rb_add_method_cfunc 1510 class.c            rb_add_method_cfunc(klass, rb_intern(name), func, argc, METHOD_VISI_PUBLIC);
rb_add_method_cfunc 1516 class.c            rb_add_method_cfunc(klass, rb_intern(name), func, argc, METHOD_VISI_PROTECTED);
rb_add_method_cfunc 1522 class.c            rb_add_method_cfunc(klass, rb_intern(name), func, argc, METHOD_VISI_PRIVATE);
rb_add_method_cfunc  176 method.h       void rb_add_method_cfunc(VALUE klass, ID mid, VALUE (*func)(ANYARGS), int argc, rb_method_visibility_t visi);