James Munns: `postcard-rpc` question: (how) can i put something with a lifetime in the `Context`? i need to use the `adafruit-seesaw` crate and it has a weird custom wrapper around i2c & delay which you instantiate like this: https://github.com/alexeden/adafruit-seesaw/blob/56780b3fba774c2570df55e40c2fa7cf57ccf651/examples/rotary_encoder_test.rs#L25-L28
that way you end up with a `RefCell`.

i had [proposed an alternative API](https://github.com/alexeden/adafruit-seesaw/pull/18) which allows using `embedded-hal-bus` structures directly with which i can add it to the `Context`. but so far this hasn't made it in yet (the maintainer [started an alternative PR](https://github.com/alexeden/adafruit-seesaw/pull/21) with the same goal but hasn't had time to finish it yet). but as long as that's not in i need a way to still use the sensor.
worst-case i'll have to depend on the patched version of the library, but i was hoping that i can use the currently available version (well, current git HEAD, anyway - without the latest commit it needs nightly rust)