digraph example1 {
    test1[label="test1"];
    test2[label="test2"];
    test3[label="test3"];
    test4[label="test4"];
    test5[label="test5"];
    test6[label="test6"];
    test2 -> test1[label=""];
    test1 -> test3[label=""];
    test4 -> test1[label=""];
    test6 -> test5[label=""];
}