What is the code name of the person born in Liverpool?
CREATE TABLE "characters" (
  "code_name" text,
  "function_figure" text,
  "real_name" text,
  "birthplace" text,
  "serial_number" text,
  "primary_military_speciality" text,
  "secondary_military_speciality" text
);
SELECT "code_name" FROM "characters" WHERE "birthplace"='liverpool';