Prev N move the iterator backwards N times. If it was invalid, first move it the last location in its associated dictionary, then move it backwards from there N - 1 times. First move the iterator to the first location in its associated dictionary. Last move the iterator to the last location in its associated dictionary. Key return the key stored at the current location of the iterator.
Data return the data stored at the current location of the iterator.
Set Data change the data stored the current location of the iterator. Comments, suggestions, bug fixes, etc, are welcome .