Macro simplify

macro_rules! simplify {
    ($e:expr; Result) => { ... };
    ($e:expr; Err) => { ... };
    ($e:expr; Option) => { ... };
    ($e:expr; None) => { ... };
    ($e:expr; Result; $v:expr) => { ... };
    ($e:expr; Err; $v:expr) => { ... };
    ($e:expr; Option; $v:expr) => { ... };
    ($e:expr; None; $v:expr) => { ... };
}

Simplfy an error-forwarding match block.