What is the production code of the episode written by Jack Carrerrow?
CREATE TABLE table_20967430_4 (prod_code VARCHAR, written_by VARCHAR)
SELECT prod_code FROM table_20967430_4 WHERE written_by = "Jack Carrerrow"
### Context: CREATE TABLE table_20967430_4 (prod_code VARCHAR, written_by VARCHAR) ### Question: What is the production code of the episode written by Jack Carrerrow? ### Answer: SELECT prod_code FROM table_20967430_4 WHERE written_by = "Jack Carrerrow"