pub fn new_client(
genesis_block_number: u64,
config: &Configuration,
executor: WasmExecutor<ExtendedHostFunctions<ExtendedHostFunctions<SubstrateHostFunctions, SenderAddressRecoveryOverride>, PublicKeyToHashOverride>>,
storage_overrides: Arc<Mutex<StorageOverrides>>,
) -> Result<(Arc<Client>, Arc<Backend>, KeystorePtr, TaskManager), Error>