Which locomotive class had 5 items made?
CREATE TABLE "west_donegal_railway" (
  "class" text,
  "type" text,
  "fleet_numbers" text,
  "quantity_made" real,
  "manufacturer" text,
  "date_made" real,
  "date_withdrawn" text
);
SELECT "class" FROM "west_donegal_railway" WHERE "quantity_made"=5;