In this exercise you will learn how to write a *Board Support Crate* (or BSC, also known as a *Board Support Package*) by implementing support for handling button presses, and support for using the UARTE peripheral.
The template `down-the-stack/dk_bsc/src/lib.rs` already contains the LED and Timer implementations. Add your code to the designated lines. You'll find a `//todo!` there.
This program will not call any of the functions you are implementing, so it does not matter if they are incomplete. It will refuse to build if there are errors present in the `lib.rs`!
The `lib.rs` has an attribute `#![deny(missing_docs)]`. This means, that missing doc comments for structs are returned as compiler errors, to remind you to document your work properly.
Go to [Nordic Infocenter](https://infocenter.nordicsemi.com/topic/ug_nrf52840_dk/UG/dk/intro.html) to download the User Guide. You can find all the information that is relevant to this exercise in there.