import stringify = require("csv-stringify"); let stream: stringify.Stringifier; stringify([["1", "2", "3"], ["4", "5", "6"]], (error: Error, output: string): void => { // nothing }); stringify([["1", "2", "3"], ["4", "5", "6"]], { delimiter: "," }, (error: Error, output: string): void => { // nothing }); stream = stringify({ delimiter: "," }); stream.write(["1", "2", "3"]); const transform: NodeJS.ReadWriteStream = stream; stream = stringify();