No examples for writing/changing values - how to update an attribute?

[kevinbader]

Hi,

I struggle to figure out how to do a simple check-and-update for an attribute:

use indoc::indoc;
use kdl::{KdlDocument, KdlEntry, KdlNode, KdlValue};

fn main() {
    let doc = indoc! {r#"
        foo "bar"
    "#};
    println!("{doc}");
    let mut doc: KdlDocument = doc.parse()?;
    let val = doc.get_arg_mut("foo").unwrap();
    *val = KdlValue::String(String::from("oof"));
    println!("{doc}");
}

This compiles, but doc is not changed. What am I missing?