Function collect_hypergraph_transitive_closure_paths 

pub fn collect_hypergraph_transitive_closure_paths<N, F>(
    graph: &BTreeMap<N, BTreeSet<N>>,
    label: F,
) -> (Vec<HypergraphClosurePath<N>>, Vec<Vec<String>>)
where
    N: Clone + Ord,
    F: FnMut(&N) -> String,