You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: genesis_helpers.rs
    path of file: ./repos/nearcore/integration-tests/src
    
    the code of the file until where you have to start completion: use near_async::time::Clock;
use near_chain::rayon_spawner::RayonAsyncComputationSpawner;
use near_chain::types::ChainConfig;
use near_chain::{Chain, ChainGenesis, DoomslugThresholdMode};
use near_chain_configs::Genesis;
use near_epoch_manager::shard_tracker::ShardTracker;
use near_epoch_manager::EpochManager;
use near_primitives::block::{Block, BlockHeader};
use near_primitives::hash::CryptoHash;
use near_store::genesis::initialize_genesis_state;
use near_store::test_utils::create_test_store;
use nearcor
    
pub fn genesis_block(genesis: &Genesis) -> Block {
    let dir = tempdir().unwrap();
    let store = create_test_store();
    initialize_genesis_state(store.clone(), genesis, None);
    let chain_genesis = ChainGenesis::new(&genesis.config);
    let epoch_manager = EpochManager::new_arc_handle(store.clone(), &genesis.config);
    let shard_tracker = ShardTracker::new_empty(epoch_manager.clone());
    let runtime =
        NightshadeRuntime::test(dir.path(), store, &genesis.config, epoch_manager.clone());
    let chain = Chain::new(
        Clock::real(),
        epoch_manager,
        shard_tracker,
        runtime,
        &chain_genesis,
        DoomslugThresholdMode::TwoThirds,
        ChainConfig::test(),
        None,
        Arc::new(RayonAsyncComputationSpawner),
    )
    .unwrap();
    chain.get_block(&chain.genesis().hash().clone()).unwrap()
}