{"ast_node_type":"variable","tokens":[{"end":83,"kind":"keyword","start":0,"text":"let"}]}
        let mut consumed_cgu_names = cgu_contents.remove(&cgu_src.name()).unwrap();
        // `cgu_src` before.
        cgu_contents.get_mut(&cgu_dst.name()).unwrap().append(&mut consumed_cgu_names);