useerreur::*;/// Demonstrates full catch.
/// The programmer is responsible for customizing helpful error message.
fnmain()->Resultat<()>{let path ="/impossible/path/!@#$%^&*()_+.file";// The bloody `File::open` will show "No such file or directory (os error 2)".
// When you see this message, you have no idea which file is missing.
// Use full catch to generate helpful error message .
let _file =std::fs::File::open(path).catch("CannotOpenFile", path)?;Ok(())}