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_57 (launched VARCHAR, builder VARCHAR)
### Question:
what is the launched date when the builder is john brown, clydebank?
### Answer:
SELECT launched FROM table_name_57 WHERE builder = "john brown, clydebank"