fill = white
linewid *= 0.5
circle "C0" fit
circlerad = previous.radius
arrow
circle "C1"
arrow
circle "C2"
arrow
circle "C4"
arrow
circle "C6"
arrow
circle "C7"
circle "C3" at dist(C2,C4) heading 30 from C2
arrow
circle "C5"
arrow from C2 to C3 chop
arrow from C5 to C6 chop

box height C3.y-C2.y \
    width (C7.e.x-C0.w.x)+linewid \
    with .w at 0.5*linewid west of C0.w \
    behind C0 \
    fill 0xc6e2ff thin color gray
box same \
    width (C5.e.x-C3.w.x)+linewid \
    with .sw at 0.35*linewid north of C2.n \
    fill 0x9accfc
"main branch" below at 2nd last box.s
"task branch" above at last box.n