Macro tokens 

macro_rules! tokens {
    (Symbols {
        Single {
            $($sym:literal => $variant:ident),* $(,)?
        }, Either {
            $($sym2:literal =>  $sym3:literal => $variant2:ident, $variant3:ident ),* $(,)?
        }
    }, Number {
        $($trail_enum:ident($trail_type:ty)),+ $(,)?
    },
    Keyword {
        $($x:literal => $name:ident),* $(,)?
    }
    ) => { ... };
}

To be done