human
Considering the provided database schema and associated query, produce SQL code to retrieve the answer to the query. 
###Database Schema: Former country name, Former codes, Period of validity, ISO 3166-3 code, New country names and codes
###Question: Name the former codes for  merged into panama ( pa , pan , 591 )
gpt
SELECT Former codes FROM table WHERE New country names and codes = Merged into Panama ( PA , PAN , 591 )