Function collect_chain_hashes 

fn collect_chain_hashes<C>(
    chain: Option<C>,
    db: &ZebraDb,
    intersection: Option<Hash>,
    stop: Option<Hash>,
    max_len: u32,
) -> Vec<Hash>
where
    C: AsRef<Chain>,

Returns a list of block::Hashes in the chain, following the intersection with the chain.

See find_chain_hashes() for details.