Function append_extension 

pub fn append_extension<P: AsRef<Path>, E: AsRef<str>>(
    path: P,
    additional_extension: E,
) -> PathBuf

Appends specified extension to the path.

Examples

let path = Path::new("foo.bar");
let new_path = append_extension(path, "baz");
assert_eq!(new_path, Path::new("foo.bar.baz"))