code: public Graph<K, VV, EV> reverse() throws UnsupportedOperationException {
  		DataSet<Edge<K, EV>> reversedEdges = edges.map(new ReverseEdgesMap<>()).name("Reverse edges");
  		return new Graph<>(vertices, reversedEdges, this.context);
  	}
docs: Reverse the direction of the edges in the graph.
  
  @return a new graph with all edges reversed
  @throws UnsupportedOperationException