Who wrote episode 122 in the series?
CREATE TABLE "table1_26866434_1" (
  "series_num" real,
  "season_num" real,
  "title" text,
  "director" text,
  "writer" text,
  "original_air_date" text
);
SELECT "writer" FROM "table1_26866434_1" WHERE "series_num"=122;