Macro hexutil::impl_from_hex

macro_rules! impl_from_hex {
    ($ty:ident, $len:expr, |$data:ident| $from_hex:expr $(,)?) => { ... };
    ($ty:ident, $len:expr, |$data:ident| $from_hex:expr, [$($preset:ident),* $(,)?] $(,)?) => { ... };
}

Implement common traits for binary representable data (from hex only).

See crate-level documentation for more information.