Expose Sink type from relay-runtime

[jaroslav-kubicek]

I want to suggest exporting Sink & Source types so they can be used to type the argument of Observable.create, e.g. something like this:

import { Observable } from 'relay-runtime';

const responseHandler = () => {} // Here I would like to use either Source or Sink types

export const createRequestHandler =
  (customFetcher: Fetcher) =>
  (request: RequestParameters, variables: Variables, cacheConfig: CacheConfig) => {
    const observable = Observable.create(sink => {
      void customFetcher(request, variables, cacheConfig)
        .then(responseHandler(sink))
        .catch((error: Error) => {
          sink.error(error);
        })
        .then(() => {
          sink.complete();
        });
    });

    return observable;
  };

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@alunyov merged this pull request in 5c7555b.