Macro abortable_parser::with_err

macro_rules! with_err {
    ($i : expr, $f : ident! ($($args : tt) *), $e : expr) => { ... };
    ($i : expr, $f : ident($($args : tt) *), $e : expr) => { ... };
    ($i : expr, $f : ident, $e : expr) => { ... };
}

Replaces the the sub error in a Fail case with one of your own errors.