What is the manufacturer, found under the Built column, that made locomotives with a Fuel/Trans of diesel-electric?
CREATE TABLE "diesel_locomotives" (
  "name" text,
  "built" text,
  "wheels" text,
  "fuel_trans" text,
  "status" text,
  "colour" text
);
SELECT "built" FROM "diesel_locomotives" WHERE "fuel_trans"='diesel-electric';