Function gen_rpc_module 

fn gen_rpc_module(
    genesis_number: u64,
    spawn_handle: SpawnTaskHandle,
    client: Arc<Client>,
    transaction_pool: Arc<TransactionPoolHandle>,
    keystore: KeystorePtr,
    system_rpc_tx: TracingUnboundedSender<Request<Block>>,
    impl_name: String,
    impl_version: String,
    chain_spec: &dyn ChainSpec,
    state_pruning: &Option<PruningMode>,
    blocks_pruning: BlocksPruning,
    backend: Arc<Backend>,
) -> Result<RpcModule<()>, Error>