Derive Macro Value 

#[derive(Value)]
{
    // Attributes available to this derive:
    #[sofie]
    #[sensitive]
}

#[sensitive] masks it in Debug. As a handler’s input it is read from the body field named after the type: cancel(order: Order, cancel_reason: CancelReason) takes { "cancel_reason": … }, and Option<CancelReason> takes it or nothing.