Macro variant 

macro_rules! variant {
    (($($repeated: ty),*), $value: expr) => { ... };
    (($($repeated: ty,)*), $value: expr) => { ... };
    ($name_type: ty, $value: expr) => { ... };
    ($name_type: ty, $value: expr, $name: expr) => { ... };
}

A macro to ease the creation of Variants. See frunk::field! for usage.