    g = vtk.vtkMutableDirectedGraph()
    latitude = vtk.vtkDoubleArray()
    latitude.SetName('latitude')
    longitude = vtk.vtkDoubleArray()
    longitude.SetName('longitude')
    for i in range(-90, 90, 10):
--
    graph = vtkMutableDirectedGraph()
    # Create a graph
    v1 = graph.AddVertex()
    v2 = graph.AddVertex()
    v3 = graph.AddVertex()

--
    graph = vtkMutableDirectedGraph()

    v1 = graph.AddVertex()
    v2 = graph.AddVertex()
    graph.AddEdge(v1, v2)

--
    graph = vtkMutableDirectedGraph()

    v1 = graph.AddVertex()
    v2 = graph.AddVertex()
    v3 = graph.AddVertex()
    graph.AddEdge(v1, v2)
--
    graph = vtkMutableDirectedGraph()

    v1 = graph.AddVertex()
    v2 = graph.AddChild(v1)
    graph.AddChild(v1)
    graph.AddChild(v2)
--
    graph = vtkMutableDirectedGraph()

    a = graph.AddVertex()
    b = graph.AddChild(a)
    c = graph.AddChild(a)
    d = graph.AddChild(b)
--
    g = vtkMutableDirectedGraph()

    # Create 3 vertices
    v1 = g.AddVertex()
    v2 = g.AddVertex()
    v3 = g.AddVertex()
--
    g = vtkMutableDirectedGraph()

    v1 = g.AddVertex()
    v2 = g.AddVertex()
    v3 = g.AddVertex()

--
    g = vtkMutableDirectedGraph()

    v1 = g.AddVertex()
    v2 = g.AddVertex()

    g.AddGraphEdge(v1, v2)
