Function setup_engine_with_connection 

pub async fn setup_engine_with_connection<N>(
    num_nodes: usize,
    chain_spec: Arc<N::ChainSpec>,
    is_dev: bool,
    tree_config: TreeConfig,
    attributes_generator: impl Fn(u64) -> <<N as NodeTypes>::Payload as PayloadTypes>::PayloadBuilderAttributes + Send + Sync + Copy + 'static,
    connect_nodes: bool,
) -> Result<(Vec<NodeHelperType<N, BlockchainProvider<NodeTypesWithDBAdapter<N, TmpDB>>>>, TaskManager, Wallet)>
where
    N: NodeBuilderHelper,
    LocalPayloadAttributesBuilder<N::ChainSpec>: PayloadAttributesBuilder<<N::Payload as PayloadTypes>::PayloadAttributes>,

Creates the initial setup with num_nodes started and optionally interconnected.