The German Greens have a similar, tough less radical system. On one hand, on no post do they have a single top leader - both the party and the fraction are double-headed. On the other hand, there is a strict prohibition of holding multiple offices of different kind: you can be either in the government, or a federal or state parliamentary fraction, or in the party leadership, but not in more than one of these.

_{*Lunatic*, n.
One whose delusions are out of fashion.}