basics vs advanced needs revisit

[Akuli]

{**dict1, **dict2} for example is a pretty basic thing, shouldn't be in "advanced" section

[Akuli]

Maybe it should be split into 3 parts:

• basics (how to loop over lists or use dicts or files, ...)
• handy things (defaultdict, counter etc)
• advanced things (custom __len__ method and stuff)

I think overriding __len__ method and other things should just be deleted. They don't belong in this tutorial (but maybe a notice about avoiding too much magic would be good)