digraph block {
    N0[label="entry"];
    N1[label="exit"];
    N2[label="expr 3"];
    N3[label="expr 4"];
    N4[label="expr 3 + 4"];
    N5[label="stmt 3 + 4;"];
    N6[label="block { 3 + 4; }"];
    N0 -> N2;
    N2 -> N3;
    N3 -> N4;
    N4 -> N5;
    N5 -> N6;
    N6 -> N1;
}