public WithSingleDependencyChain()
{
_graph = new DependencyGraph <string>();
_graph.AddNode("3");
_graph.AddNode("0");
_graph.AddNode("1");
_graph.AddNode("2");
_graph.Connect("3", "1");
_graph.Connect("3", "2");
_graph.Connect("2", "1");
_graph.Connect("1", "0");
}