Serialize and Deserialize

command Foo {
    ...

    seal {
        let bytes = serialize(this)
        return envelope::new(bytes)
    }

    open {
        let fields = deserialize(envelope::payload(envelope))
        return fields
    }

    ...
}

These functions turn command structs into bytes and vice versa.

serialize() takes a struct argument (of any kind) and produces a serialized bytes representation. It can only be used in a seal block.

deserialize() takes a bytes argument and produces a struct. It can only be used inside a open block.