LISTING 4: Reimplement procedure b as standalone procedure 
SQL> create or replace procedure B
  2  as
  3  begin
  4          null;

  5  end;
  6  /
Procedure created.

SQL> select object_type, object_name, status
  2  from user_objects

  3  where status = 'INVALID'
  4  order by object_type, object_name
  5  /

OBJECT_TYPE      OBJECT_NAME            STATUS
------------     --------------------   ----------------
PROCEDURE        A                      INVALID