Pin-Sho Feng

 @PaulWoitaschek I had a requirement for a similar (though not exactly the same operator) and ended up implementing [my own](https://dev.to/psfeng/a-story-of-building-a-custom-flow-operator-buffertimeout-4d95) (final implementation at the end), if it helps.

Good point. What if we pass some kind of `BaseUrl` object to the `CallSpec`'s builder? This `BaseUrl` instance would be held by `XingApi` and we would be able to change...

I'm seeing this with `npm run develop` too, tried removing the import from `gatsby-ssr.js` but nothing changed. Using version `0.2.0-beta.4`.