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_28019988_2 (series__number VARCHAR, production_code VARCHAR)
### Question:
What is the series number for the episode with production code bdf109?
### Answer:
SELECT series__number FROM table_28019988_2 WHERE production_code = "BDF109"