Session03

List_lab homework from session03
Rot13 homework from Session 3
Though it shouldn't make much difference in this particular case, `isinstance()` is preferable to `type()`. The upshot is that `isinstance()` will return `True` if the object is of the same class or a sublcass of the class you're comparing it to  while `type()` will not. See [the docs](https://docs.python.org/2/library/functions.html#isinstance), [StackOverflow](http://stackoverflow.com/questions/1549801/differences-between-isinstance-and-type-in-python), and this [succinct explanation](https://stereochro.me/ideas/type-vs-isinstance#fn:caveat).