1: Pie with internal labels.
2: Pie with external labels and precision=0.
3/4: Two pies with internal and external labels with a constant radius.
5/6: Pie with internal custom labels and custom colors (#6 is rotated).
7: Degenerated pie with 1 element.
8: Degenerated pie with 1 positive elements (out of 5).
That's all Folks!