code: public static Set<Node> prepareSingleNodeSetFromSets(Set<Set<BioPAXElement>> sets, Graph graph)
  	{
  		Set<BioPAXElement> elements = new HashSet<BioPAXElement>();
  		for (Set<BioPAXElement> set : sets)
  		{
  			elements.addAll(set);
  		}
  		return prepareSingleNodeSet(elements, graph);
  	}
docs: Gets the related wrappers of the given elements in the sets.
  @param sets Sets of elements to get the related wrappers
  @param graph Owner graph
  @return Related wrappers in a set