mrb_undef_class_method_id(mrb_state *mrb, struct RClass *c, mrb_sym name)
{
  mrb_undef_method_id(mrb,  mrb_class_ptr(mrb_singleton_class(mrb, mrb_obj_value(c))), name);
}
mrb_undef_class_method_id(mrb_state *mrb, struct RClass *c, mrb_sym name)
{
  mrb_undef_method_id(mrb,  mrb_class_ptr(mrb_singleton_class(mrb, mrb_obj_value(c))), name);
}