func defaultMsgIdProvider(m: Message): Result[MessageId, ValidationResult] {.
    ...raises: [], tags: [], forbids: [].}

proc init(T: type Message; peer: Opt[PeerInfo]; data: sink seq[byte];
          topic: string; seqno: Opt[uint64]; sign: bool = true): Message {.
    ...gcsafe, raises: [], raises: [].}

proc init(T: type Message; peerId: PeerId; data: sink seq[byte]; topic: string;
          seqno: Opt[uint64]): Message {....gcsafe, raises: [], raises: [].}

proc sign(msg: Message; privateKey: PrivateKey): CryptoResult[seq[byte]] {.
    ...raises: [], tags: [RootEffect], forbids: [].}

proc verify(m: Message): bool {....raises: [], tags: [RootEffect, WriteIOEffect],
                                forbids: [].}