Request: Streaming completions

Thanks for this well crafted package!

I have a request, could you please add Streaming to completions?
As described in the API:
stream boolean Optional Defaults to false
Whether to stream back partial progress. If set, tokens will be sent as data-only [server-sent events] as they become available, with the stream terminated by a data: [DONE] message.

With media type "application/octet-stream"