Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_23937219_3 (prod_code INTEGER, series__number VARCHAR)
### Question:
What is the production code for episode 31 in the series?
### Answer:
SELECT MIN(prod_code) FROM table_23937219_3 WHERE series__number = 31