If I define an additive group according to the instructions in the documentation, it still will not satisfy the AdditiveGroup trait, and I can't do addition with it (e.g. element + element).

use alga::general::{AbstractMagma, Additive, AdditiveGroup, Identity, Inverse}; // 0.7.2
use alga_derive::Alga; // 0.7.1

#[derive(Alga, Clone, Copy, PartialEq, Debug)]
#[alga_traits(Group(Additi

Describe the bug
Documentation example is broken

To Reproduce
Steps to reproduce the behavior:

1. Go to 'https://github.com/ntrupin/abstractml/tree/master/docs/examples'
2. See error

Expected behavior
The page displays the proper compiled html source

Screenshots
![image](https://user-images.githubusercontent.com/37413895/69005868-b5e55b00-098c-11ea-9442-822dec285555.

I think I never announce a couple of projects I've made using astq some time ago that I think the maintainers will be happy to see In particular this playground which uses monaco-editor so users can edit astq queries with syntax highlight, autocomplete, error handling inline help, and online evaluation against the target code which in my case is TypeScript /JavaScript/JSX/TSX. I thought the author