Function serve 

async fn serve<R: Radio>(
    mac: &AsyncRefCell<Mac<TokioPlatform<R, TokioFileCounterStore, TokioFileKeyValueStore>, IDENTITIES, PEERS, CHANNELS, ACKS, TX, FRAME, DUP>>,
    identity: SoftwareIdentity,
    target: PublicKey,
    endpoint: MeshEndpoint,
)
where
    R::Error: Debug,