Name the class with call sign of k220cp
CREATE TABLE "external_links" (
  "call_sign" text,
  "frequency_m_hz" real,
  "city_of_license" text,
  "erp_w" real,
  "class" text,
  "fcc_info" text
);
SELECT "class" FROM "external_links" WHERE "call_sign"='k220cp';