//@ low-level data-structure like a doubly-linked list, it makes sense to implement an efficient
//@ version once, that is unsafe internally, but that can be used without any risk by safe client
//@ code.
+
//@ As usually, we start by defining the types. Everything is parameterized by the type `T` of the
//@ data stored in the list.
// A node of the list consists of the data, and two node pointers for the predecessor and successor.
}
// ## The End
-
//@ Congratulations! You completed Rust-101. This was the last part of the course. I hope you
//@ enjoyed it. If you have feedback or want to contribute yourself, please head to the
//@ [Rust-101](https://www.ralfj.de/projects/rust-101/) website fur further information. The entire