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_name_28 (serial_numbers VARCHAR, class VARCHAR)
### Question:
What are the serial numbers for the locomotives of Class 4-8-4 — oooooooo — northern?
### Answer:
SELECT serial_numbers FROM table_name_28 WHERE class = "4-8-4 — oooooooo — northern"