Oracle 12c accessible by clause

PACKAGE Helper authid Definer accessible BY(Good_Unit,Bad_Unit)
IS
PROCEDURE p;
END Helper;
PACKAGE body Good_Unit
IS
PROCEDURE p
IS
BEGIN
  Helper.p();
  ...
END p;
END Good_Guy;
PACKAGE body Bad_Unit
IS
PROCEDURE p
IS
BEGIN
  Helper.p();
  ...
END p;
END Bad_Guy;