digraph {
    Node [shape="point"]

    Root -> ExecRoot [label="username"]
    ExecRoot -> Input [label="'input'"]
    ExecRoot -> LastInput [label="'last_input'"]
    ExecRoot -> Output [label="'output'"]
    ExecRoot -> LastOutput [label="'last_output'"]
    ExecRoot -> CurFrame [label="'frame'"]
    CurFrame -> Table [label="'symbols'"]
    CurFrame -> Inst [label="'IP'"]
    CurFrame -> EvalStack [label="evalstack'"]
    CurFrame -> Phase [label="'phase'"]
    CurFrame -> ReturnValue [label="'returnvalue'"]
}