List Iterator Wish List

• Initialize at first element of a list
• Initialize at last element of a list
• Increment to next item on a list
• Decrement to previous item on a list
• Return current item on list
• Detect end of iteration (past last or past first)
• Compare iterators for equality
• Detect whether iterator is at a valid item
• Proper type
• Generic class
• All operations run in time O(1)