Some strings looks like they're meant to be f-strings but are missing the `f` prefix meaning variable interpolation won't happen. https://github.com/robinhood/faust/blob/01b4c0ad8390221db71751d80001b0fd879291e2/faust/streams.py#L210 I found this issue automatically. I'm a bot. Beep Boop 🦊. See other issues I found in your repo [here](https://codereview.doctor/robinhood/faust)