Function validate_tipsets 

pub fn validate_tipsets<DB, T>(
    genesis_timestamp: u64,
    chain_index: Arc<ChainIndex<Arc<DB>>>,
    chain_config: Arc<ChainConfig>,
    beacon: Arc<BeaconSchedule>,
    engine: &MultiEngine,
    tipsets: T,
) -> Result<()>
where
    DB: Blockstore + Send + Sync + 'static,
    T: Iterator<Item = Arc<Tipset>> + Send,