A ℘ (IndexedPowerSet) constructed with a collection with elements of type E can construct
an Iterator which enumerates all possible subsets (of type Collection<E>) of the
collection used to construct the PowerSet.
(Changed in version 2.9.0) The behavior of scanRight has changed. The previous behavior can be reproduced with scanRight.reverse.
(Changed in version 2.9.0) transpose throws an IllegalArgumentException if collections are not uniformly sized.