For instance:

If I am iterating through a Python list ['a','b','c'] how do I get back to element 'a' once I have reached 'c'?

If you mean to do a loop like if your list was in circle, simply use the modulo operator :

mylist = ["a", "b", "c"]
for i in range(n): # set n to desired valueprint(mylist[i % len(mylist)])