/// This makes sure the `README.md` contains code that compiles. `cargo test` currently
/// doesn't support checking external artifacts.
///
/// This macro was pulled off of [Run doc tests on README](https://github.com/rust-lang/cargo/issues/383#issuecomment-720873790).
/// It introduces an empty `extern "C"` block, and adds a `#[doc]` attribute that's
/// assigned to an arbitrary string literal.
///
external_doc_test!;