Reimplementing the module `itertools` for fun and profit

In this hands-on tutorial we will reinvent the wheel and implement the module itertools in plain Python.

We'll do that because that will teach us a lot about Python:

• how generators and lazy iteration work;
• the difference between iterables and iterators;
• what the built-ins iter and next do;
• how Python handles iteration and for loops under the hood;
• what the iterator protocol is;
• how the dunder methods __iter__ and __next__ play a part in all this; and
• we'll also learn about the functions inside itertools, a module with plenty of useful tools for your day-to-day iterations.

And most importantly, we'll do it because it's genuinely fun!