CREATE TABLE table_204_131 (id DECIMAL, "tops design code" TEXT, "electrical system" TEXT, "max speed" TEXT, "weight" TEXT, "brakes" TEXT, "route availability" DECIMAL, "notes" TEXT)

what is the last tops design code on this chart ?
SELECT "tops design code" FROM table_204_131 ORDER BY id DESC LIMIT 1
SELECT "tops design code" FROM "table_204_131" ORDER BY "id" DESC NULLS LAST LIMIT 1