What is the highest First Elected, when Party is "Republican", and when District is "Louisiana 7"?
CREATE TABLE "louisiana" (
  "district" text,
  "incumbent" text,
  "party" text,
  "first_elected" real,
  "results" text
);
SELECT MAX("first_elected") FROM "louisiana" WHERE "party"='republican' AND "district"='louisiana 7';