import { Transform, TransformOptions } from 'stream';
/**
EventSource is a subclass of stream.Transform for converting a stream of objects
into `text/event-stream` style output.

You should call `res.setHeader('Content-Type', 'text/event-stream');` on your
HTTP response `res` before piping this EventSource stream into the response.

And for this use-case, you'll want to listen for onerror on the client-side,
and close() the EventSource object on the first error, otherwise it will try
to reconnect immediately when the response stream closes. As far as I know,
there is no special event you can send to trigger a complete stop.

Documentation: http://www.w3.org/TR/eventsource/

MDN is usually great, but their article on EventSource sucks:
  https://developer.mozilla.org/en-US/docs/Web/API/EventSource
*/
export declare class EventSource extends Transform {
    constructor(options?: TransformOptions);
    _transform(chunk: any, encoding: BufferEncoding, callback: (error?: Error, outputChunk?: any) => void): void;
}