Function saboten::cactusgraph::chain_pair_ultrabubble_labels

pub fn chain_pair_ultrabubble_labels(
    cactus_tree: &CactusTree<'_>, 
    chain_pairs: &FnvHashSet<ChainPair>
) -> FnvHashMap<(u64, u64), bool>

Labels chain edges as ultrabubbles if their net graphs are acyclic and bridgeless, returning a map from chain edges to true/false.