What is the type with a quantity of fewer than 6 and number(s) 5201?
CREATE TABLE "tank_locomotives" (
  "class" text,
  "number_s" text,
  "quantity" real,
  "year_s_of_manufacture" text,
  "type" text
);
SELECT "type" FROM "tank_locomotives" WHERE "quantity"<6 AND "number_s"='5201';