You can refer to the following links for more information:
- Learning Rust With Entirely Too Many Linked Lists (http://cglab.ca/~abeinges/blah/too-many-lists/book/README.html)
- Implementing the Iterator trait (https://doc.rust-lang.org/std/iter/index.html#implementing-iterator)
- Skip Lists: Done Right (https://doc.rust-lang.org/std/iter/index.html#implementing-iterator)
- Skip Lists: A Probabilistic Alternative to Balanced Trees, William Pugh (https://www.epaperpress.com/sortsearch/download/skiplist.pdf)
