What is the class of the locomotive with a 0-4-0st type?
CREATE TABLE "sligo_leitrim_and_northern_counties_rail" (
  "class" text,
  "type" text,
  "names" text,
  "quantity_made" text,
  "manufacturer" text,
  "date_made" text
);
SELECT "class" FROM "sligo_leitrim_and_northern_counties_rail" WHERE "type"='0-4-0st';