Item

        pub const Item = struct {
            /// null terminated string index
            msg: NullTerminatedString,
            node: Ast.Node.OptionalIndex,
            /// If node is .none then this will be populated.
            token: Ast.OptionalTokenIndex,
            /// Can be used in combination with `token`.
            byte_offset: u32,
            /// 0 or a payload index of a `Block`, each is a payload
            /// index of another `Item`.
            notes: u32,

            pub fn notesLen(item: Item, zir: Zir) u32 {
                if (item.notes == 0) return 0;
                const block = zir.extraData(Block, item.notes);
                return block.data.body_len;
            }
        }