what is the metlink code that opened in 1908?
CREATE TABLE table_31458 (
    "Station" text,
    "Metlink code" text,
    "Line(s)" text,
    "Service(s)" text,
    "Serves" text,
    "km from Wellington" text,
    "Fare zone(s)" text,
    "Opened" text
)
SELECT "Metlink code" FROM table_31458 WHERE "Opened" = '1908'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: what is the metlink code that opened in 1908? ### Input: CREATE TABLE table_31458 (
    "Station" text,
    "Metlink code" text,
    "Line(s)" text,
    "Service(s)" text,
    "Serves" text,
    "km from Wellington" text,
    "Fare zone(s)" text,
    "Opened" text
) ### Response: SELECT "Metlink code" FROM table_31458 WHERE "Opened" = '1908'