This code will flash the LEDs in the circle on an STM32F3 Discovery board, using the Embassy Rust libraries.
To use, you may need to add the target. I'm using Rustup, so this was just rustup target add thumbv7em-none-eabihf. You also need probe-run available on your path. This may be provided by your distribution, or installable via cargo install probe-run.
After that, cargo run should compile the code and, assuming you have the board connected via USB to the ST-Link port, flash it and run it with debug messages visible in your console.