    vertex = vtkVertex()
    for i in range(0, number_of_vertices):
        vertex.GetPointIds().SetId(i, i)

    ug = vtkUnstructuredGrid()
    ug.SetPoints(points)
--
    vertex = vtkVertex()
    vertex.GetPointIds().SetId(0, 0)

    vertices = vtkCellArray()
    vertices.InsertNextCell(vertex)

