Basically, because python classes are not iterable by default, you have to inform python that you intend to turn it into an inter object, thus returning self.

Look at it like converting an integer into a string. To do this you will need to use str(8) to convert to a string. Same with the iter object. outside classes the 'for' keyword lets Python know two things:

1. This is now an iter object

2. We will perform next() until the length of elements is exhuasted and enact StopIteration before we get an index error.

Classes are set up as objects for you to code manually basically.