public Set<Vertex> getAncestors(Vertex v) {
		Set<Vertex> seeds = new HashSet<>(11);
		seeds.add(v);
		Set<Vertex> ancestors = new HashSet<>(this.numVertices() / 20);
		Set<Vertex> newSeeds = new HashSet<>();
		Iterator<Vertex> i;
		Vertex vertex, parent;
		Edge e;

		ancestors.add(v);
		while (!seeds.isEmpty()) {
			newSeeds.clear();
			i = seeds.iterator();
			while (i.hasNext()) {
				vertex = i.next();
				e = vertices.getFirstIncomingEdge(vertex);
				while (e != null) {
					parent = e.from();
					if (ancestors.add(parent)) {
						newSeeds.add(parent);
					}
					e = edges.getNextEdgeWithSameTo(e);
				}
			}
			seeds.clear();
			seeds.addAll(newSeeds);
		}
		ancestors.add(v);
		return ancestors;
	}
Returns a set of all the vertices which are ancestors of the given vertex.
  Note: By definition a vertex is one of its own ancestors.
Ghidra/Framework/Generic/src/main/java/ghidra/util/graph/DirectedGraph.java