Go back to previous PL/SQL code with using Flashback Features

Be sure your database is enabled  FLASHBACK DATABASE.

grant flashback on user_source to <user_name>;

During the Flashbackback Retention Time,you can easily reach your previous code.

select *  from user_source as of scn timestamp_to_scn(systimestamp – 15/1440)   where name = ‘<MY_PROCEDURE_NAME>’;