When you use for item in o for some iterable object o, Python calls iter(o) and expects an iterator object as the return value. An iterator is any object which implements a next (or next in Python 2) method and an iter method. By convention, the iter method of an iterator should return the object itself (i.e. return self).
Here I'm creating a JavaScript object and converting it to a JSON string, but JSON.stringify returns " [object Object]" in this case, instead of displaying the contents of the object.
Any container is a relatively small object that holds a reference to some data storage (usually an array) outside the actual container object - and that in turn holds references to the actual objects you added to the container. So the question how much memory a List takes is not even well defined - the size of the list object itself, memory allocated by the list object, total size for ...
Your body breaks down all the food you eat into something smaller. Some foods turn into amino or fatty acids, while others turn into sugar. It’s not the white sugar you might put into your coffee.