classes: {
  q: {
    shape: diamond
  }
  start: {
    shape: oval
    label: Début
    near: top-center
  }
  end: {
    shape: oval
    label: Fin
    near: bottom-center
  }
  comment: {
    style: {
      stroke-dash: 3
    }
  }
  y: {
    source-arrowhead.label: yes
    style.stroke: green
    source-arrowhead.style.font-color: green
  }
  n: {
    source-arrowhead.label: no
    style.stroke: red
    source-arrowhead.style.font-color: red
  }
}
direction: down
start.class: start
end.class: end