g.addNode("Java");
g.addNode("Python");
g.addNode("C++");
g.addNode("Perl");
g.addNode("C#");
g.addNode("Programming Language");
g.addEdge("is a", "Java", "Programming Language");
g.addEdge("is a", "C#", "Programming Language");
g.addEdge("is a", "C++", "Programming Language");
g.addEdge("is a", "Perl", "Programming Language");