Macro optfield 

macro_rules! optfield {
    (
    $(#[$attr:meta])*
    $vis:vis struct $name:ident {
        $(
            $(#[$field_attr:meta])*
            $field_vis:vis
            $field:ident : $ty:ty
        ),* $(,)?
    }
    ($new:ident)
) => { ... };
}

A macro to generate a new struct with fields wrapped in Option.