How many titles were written by Don Shank and Genndy Tartakovsky?
CREATE TABLE "table1_2156758_4" (
  "no_in_series" text,
  "no_in_season" text,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text
);
SELECT COUNT("title") FROM "table1_2156758_4" WHERE "written_by"='Don Shank and Genndy Tartakovsky';