CREATE TABLE table_74207 ("Series #" FLOAT, "Season #" TEXT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "U.S. viewers  ( millions ) " TEXT)

Who wrote the episode titled 'An Old-fashioned Piano Party'?
SELECT "Written by" FROM table_74207 WHERE "Title" = 'An Old-Fashioned Piano Party'
SELECT "Written by" FROM "table_74207" WHERE "Title" = 'An Old-Fashioned Piano Party'