pub fn spawn_tracing_tasks<B, C, BE>(
    rpc_config: &RpcConfig,
    prometheus: Option<Registry>,
    params: SpawnTasksParams<'_, B, C, BE>
) -> RpcRequesters
where C: ProvideRuntimeApi<B> + BlockOf + StorageProvider<B, BE> + HeaderBackend<B> + HeaderMetadata<B, Error = Error> + 'static + BlockchainEvents<B> + Send + Sync, C::Api: EthereumRuntimeRPCApi<B> + DebugRuntimeApi<B> + BlockBuilder<B>, B: BlockT<Hash = H256> + Send + Sync + 'static, B::Header: HeaderT<Number = u32>, BE: Backend<B> + 'static, BE::State: StateBackend<BlakeTwo256>,