Table: tv_episode_data_14
Columns: no_in_series
no_in_season
title
directed_by
written_by
original_air_date
production_code
u_s_viewers_millions

Question: Name the production code for number in season being 21
SQL: SELECT "production_code" FROM tv_episode_data_14 WHERE "no_in_season" = '21'

Question: Name the production code by paul lieberstein
SQL: SELECT "production_code" FROM tv_episode_data_14 WHERE "written_by" = 'Paul Lieberstein'