Workaround for WHATWG streams in TypeScript

streams.ts

import {
  ReadableStream as WhatWGReadableStream,
  TransformStream as WhatWGTransformStream,
  WritableStream as WhatWGWritableStream
} from 'whatwg-streams';

export type ReadableStream<R> = WhatWGReadableStream<R>;
export const ReadableStream: typeof WhatWGReadableStream = (self as any).ReadableStream;

export type WritableStream<W> = WhatWGWritableStream<W>;
export const WritableStream: typeof WhatWGWritableStream = (self as any).WritableStream;

export type TransformStream<R, W> = WhatWGTransformStream<R, W>;
export const TransformStream: typeof WhatWGTransformStream = (self as any).TransformStream;