If you want to help, there's a whole bunch of failing test fixtures (borrowed from the lovely [shellcheck](https://github.com/koalaman/shellcheck project)). You can start with reading the grammar. The grammar defines how text will be matched, while the corresponding rule callbacks in overrides.js defines the way those matches will be processed into AST nodes. Be sure to read the comments as there's a tiny bit of magic going on. If you get stuck trying to fix a test case, email me. GitHub issue notifications almost never get my attention.