chunkBy method
Returns an iterator over the slice producing non-overlapping runs of elements
using the predicate to separate them.
[1, 1, 1, 3, 3]
=> [[1, 1, 1], [3, 3]]
for (a, b) => a == b
The predicate is called for every pair of consecutive elements.
Implementation
Iter<Slice<T>> chunkBy(bool Function(T, T) compare) {
return Iter(_chunkByHelper(compare).iterator);
}