Which prefecture is in Hubei province and Enshi county?
CREATE TABLE "by_county" (
  "province" text,
  "prefecture" text,
  "county" text,
  "tujia_population" real,
  "pct_of_china_s_tujia_population" text
);
SELECT "prefecture" FROM "by_county" WHERE "province"='hubei' AND "county"='enshi';