What's the purpose of the `Word` AST type?

Looking at the [`Word`](https://docs.rs/brush-parser/0.2.16/brush_parser/ast/struct.Word.html) AST type, it appears to just be a wrapper around a `String` with no extra functionality. I see that there's a [`Word::flatten`](https://docs.rs/brush-parser/0.2.16/brush_parser/ast/struct.Word.html#method.flatten) method, but this just returns the string itself.

Am I overlooking something?