digraph Taskflow {
newrank=true;
#columns
subgraph {
p00[label="stage-0-a"];
p10[label="stage-0-b"];
p20[label="stage-0-c"];
p30[label="stage-0-d"];
}

subgraph  {
p01[label="stage-1-a"];
p11[label="stage-1-b"];
p21[label="stage-1-c"];
p31[label="stage-1-d"];
}

subgraph  {
p02[label="stage-2-a"];
p12[label="stage-2-b"];
p22[label="stage-2-c"];
p32[label="stage-2-d"];
}

subgraph  {
p03[label="stage-3-a"];
p13[label="stage-3-b"];
p23[label="stage-3-c"];
p33[label="stage-3-d"];
}

subgraph cluster0 {
rank="same";
style="dashed";
p00;
p01;
p02;
p03;
}
subgraph cluster1 {
rank="same";
style="dashed";
p10;
p11;
p12;
p13;
}
subgraph cluster2 {
rank="same";
style="dashed";
p20;
p21;
p22;
p23;
}
subgraph cluster3 {
rank="same";
style="dashed";
p30;
p31;
p32;
p33;
}

p00 -> p01;
p01 -> p02;
p02 -> p03;
p10 -> p11;
p11 -> p12;
p12 -> p13;
p20 -> p21;
p21 -> p22;
p22 -> p23;
p30 -> p31;
p31 -> p32;
p32 -> p33;
p00 -> p10;
p01 -> p11;
p02 -> p12;
p03 -> p13;
p10 -> p20;
p11 -> p21;
p12 -> p22;
p13 -> p23;
p20 -> p30;
p21 -> p31;
p22 -> p32;
p23 -> p33;
}