digraph TopLevel {
    label = "TopLevel"
    compound = true
    fontname = Arial
    fontsize = 8
    bgcolor = lightcyan1
    node [
        color = black,
        fontname = Arial,
        fontsize = 8
    ]

    Engine [
        fontcolor = black,
        shape = ellipse,
        URL = "classes/Engine.html",
        color = palegoldenrod,
        style = filled,
        label = "Engine"
    ]

    Singleton [
        shape = box,
        URL = "classes/Singleton.html",
        label = "Singleton"
    ]

    Singleton -> Engine [

    ]

}