How to add headers for specific request?

Hi to all.
I’m reviewing apistar and estimate it as candidate for service(s) client.

And I don’t see proper way set unique headers for single request.
It could be need, for example, for passing header with request-id (but I think other examples could be easily found).
Is that possible?

With quick glance on the code, I see only one solution: change Client.transport.headers before each request… Directly, in very rough way.

It not looks as good solution, probably I misunderstand something?