What is the Visitor of the game on April 2?
CREATE TABLE "detroit_red_wings_4_chicago_black_hawks_" (
  "date" text,
  "visitor" text,
  "score" text,
  "home" text,
  "record" text
);
SELECT "visitor" FROM "detroit_red_wings_4_chicago_black_hawks_" WHERE "date"='april 2';