SV * _copy( SV * arg_obj, SV * second, SV * third ) {
     Number * num_obj;
     SV * obj_ref, * obj;
     printf( "_copy:%p %p %p\n", arg_obj, second, third  );
...

SV * _set_from_existing( SV * arg_obj ) {
     Number * num_obj;
     SV * obj_ref, * obj;
     printf( "_set::%p\n", arg_obj );

...