/// `foo.bar` might be replaced with `a.b` or `x.y` by replacing
/// `foo` and `bar` on their own:
///
- /// ```
+ /// ```ignore (illustrative)
/// vec![
/// Substitution { parts: vec![(0..3, "a"), (4..7, "b")] },
/// Substitution { parts: vec![(0..3, "x"), (4..7, "y")] },
///
/// or by replacing the entire span:
///
- /// ```
+ /// ```ignore (illustrative)
/// vec![
/// Substitution { parts: vec![(0..7, "a.b")] },
/// Substitution { parts: vec![(0..7, "x.y")] },