CREATE TABLE table_21550870_1 (production_code VARCHAR, written_by VARCHAR)

Name the total number of production code for episode by steve cohen & andrew dettman
SELECT COUNT(production_code) FROM table_21550870_1 WHERE written_by = "Steve Cohen & Andrew Dettman"
SELECT COUNT("production_code") FROM "table_21550870_1" WHERE "Steve Cohen & Andrew Dettman" = "written_by"