What kind of Chassis supports a Maserati Straight-6 engine with Points greater than 0 and built in the year 1955?
CREATE TABLE "complete_formula_one_world_championship_" (
  "year" real,
  "entrant" text,
  "chassis" text,
  "engine" text,
  "points" real
);
SELECT "chassis" FROM "complete_formula_one_world_championship_" WHERE "engine"='maserati straight-6' AND "points">0 AND "year"=1955;