///
/// `anyhow::Result` may be used with one *or* two type parameters.
///
/// ```rust
/// use anyhow::Result;
///
/// # const IGNORE: &str = stringify! {
/// fn demo1() -> Result<T> {...}
///            // ^ equivalent to std::result::Result<T, anyhow::Error>

/// fn demo2() -> Result<T, OtherError> {...}
///            // ^ equivalent to std::result::Result<T, OtherError>
/// # };
/// ```
///