Working through the [Fly.io distributed systems challenge](https://fly.io/dist-sys/), in Rust.

The `nebkor-maelstrom` crate is meant to be roughly equivalent to the Go Maelstrom.Node package, and
provides serde-backed data structures for messages as well as runner for processing messages from
the Maelstrom network. See `gg-echo/src/main.rs` for the simplest possible use of it.