Function verify_block 

pub async fn verify_block(
    overlay: &BlockchainOverlayPtr,
    diffs: &[SledDbOverlayStateDiff],
    module: &PoWModule,
    block: &BlockInfo,
    previous: &BlockInfo,
    verify_fees: bool,
) -> Result<()>

Verify given BlockInfo, and apply it to the provided overlay.

Note: Always remember to purge new trees from the database if not needed.