CREATE TABLE table_name_1 (production_code VARCHAR(255), original_air_date VARCHAR(255), season__number VARCHAR(255), series__number VARCHAR(255))
What is the production code of the episode before season 8, with a series number less than 31, and aired on September 21, 1995?
    
SQL: SELECT production_code FROM table_name_1 WHERE season__number < 8 AND series__number < 31 AND original_air_date = "september 21, 1995"