Macro rustemo_mod 

macro_rules! rustemo_mod {
    ($(#[$attr:meta])* $vis:vis $modname:ident, $source:expr) => { ... };
}

Loads generated parser modules from the Cargo OUT_DIR location.

Used when the parser is generated from the build.rs script.

This macro and the general idea of bootstrapping approach is based on idea from lalrpop project