IteratorSpliterator
Description:
Creates a new iterator spliterator.
Parameters:
| iterator | 
           an iterator  | 
      
| estimated_size | 
           the estimated size of the iterator, or negative if infinite, unknown, etc. If the given iterator points at some element it is included in this size.  | 
      
| size_known | 
           true if estimated_size is an accurate size, false otherwise.  |