What is the power that belongs to Class A with an Identifier of CBOC-FM?
CREATE TABLE "s_rebroadcaster_of_cbo_fm" (
  "city_of_license" text,
  "identifier" text,
  "frequency" text,
  "power" text,
  "class" text,
  "rec_net" text
);
SELECT "power" FROM "s_rebroadcaster_of_cbo_fm" WHERE "class"='a' AND "identifier"='cboc-fm';