约定

/// In documentation comments, you may use **Markdown**.
/// This includes `backticks` for code, *italics* and **bold**.
/// You can add headers in your documentation, like this:
/// # Notes
/// `Foo` is unsuitable for snafucating. Use `Bar` instead.
struct Foo {
    ...
}

/// It is considered good practice to have examples in your documentation
/// under an "Examples" header, like this:
/// # Examples
/// Code can be added in "fences" of 3 backticks.
///
/// ```
/// let bar = Bar::new();
/// ```
///
/// Examples also function as tests to ensure the examples actually compile.
/// The compiler will automatically generate a main() function and run the
/// example code as a test when cargo test is run.
struct Bar {
    ...
}