title: Python's __loader__, what is it?
body: <p>I've seen the term <code>__loader__</code> floating around some Python files and I can't find any documentation on it aside from a few brief descriptions about it's purpose, but they still don't provide enough information for me to get a good understanding of it. All I know is that it has something to do with importing modules, other than that I'm completely at a loss. What does it do? When is it used? How can I use it if at all?</p>