| import * as stream from 'stream'; | 
|   | 
| declare const isStream: { | 
|     /** | 
|     @returns Whether `stream` is a [`Stream`](https://nodejs.org/api/stream.html#stream_stream). | 
|   | 
|     @example | 
|     ``` | 
|     import * as fs from 'fs'; | 
|     import isStream = require('is-stream'); | 
|   | 
|     isStream(fs.createReadStream('unicorn.png')); | 
|     //=> true | 
|   | 
|     isStream({}); | 
|     //=> false | 
|     ``` | 
|     */ | 
|     (stream: unknown): stream is stream.Stream; | 
|   | 
|     /** | 
|     @returns Whether `stream` is a [`stream.Writable`](https://nodejs.org/api/stream.html#stream_class_stream_writable). | 
|   | 
|     @example | 
|     ``` | 
|     import * as fs from 'fs'; | 
|     import isStream = require('is-stream'); | 
|   | 
|     isStream.writable(fs.createWriteStrem('unicorn.txt')); | 
|     //=> true | 
|     ``` | 
|     */ | 
|     writable(stream: unknown): stream is stream.Writable; | 
|   | 
|     /** | 
|     @returns Whether `stream` is a [`stream.Readable`](https://nodejs.org/api/stream.html#stream_class_stream_readable). | 
|   | 
|     @example | 
|     ``` | 
|     import * as fs from 'fs'; | 
|     import isStream = require('is-stream'); | 
|   | 
|     isStream.readable(fs.createReadStream('unicorn.png')); | 
|     //=> true | 
|     ``` | 
|     */ | 
|     readable(stream: unknown): stream is stream.Readable; | 
|   | 
|     /** | 
|     @returns Whether `stream` is a [`stream.Duplex`](https://nodejs.org/api/stream.html#stream_class_stream_duplex). | 
|   | 
|     @example | 
|     ``` | 
|     import {Duplex} from 'stream'; | 
|     import isStream = require('is-stream'); | 
|   | 
|     isStream.duplex(new Duplex()); | 
|     //=> true | 
|     ``` | 
|     */ | 
|     duplex(stream: unknown): stream is stream.Duplex; | 
|   | 
|     /** | 
|     @returns Whether `stream` is a [`stream.Transform`](https://nodejs.org/api/stream.html#stream_class_stream_transform). | 
|   | 
|     @example | 
|     ``` | 
|     import * as fs from 'fs'; | 
|     import Stringify = require('streaming-json-stringify'); | 
|     import isStream = require('is-stream'); | 
|   | 
|     isStream.transform(Stringify()); | 
|     //=> true | 
|     ``` | 
|     */ | 
|     transform(input: unknown): input is stream.Transform; | 
| }; | 
|   | 
| export = isStream; |