What is guido bontempi's general classification when he has a stage of 6?
CREATE TABLE "classification_leadership" (
  "stage" text,
  "winner" text,
  "general_classification" text,
  "points_classification" text,
  "young_rider_classification" text,
  "team_classification" text
);
SELECT "general_classification" FROM "classification_leadership" WHERE "winner"='guido bontempi' AND "stage"='6';