rb_singleton_class_clone_and_attach  367 class.c            return rb_singleton_class_clone_and_attach(obj, Qundef);
rb_singleton_class_clone_and_attach  887 internal.h     VALUE rb_singleton_class_clone_and_attach(VALUE obj, VALUE attach);
rb_singleton_class_clone_and_attach  337 object.c           singleton = rb_singleton_class_clone_and_attach(obj, clone);