It all depends on what you understand under "problem", "coding" and "practice". For example, my first guess is you might be interested in looking up whatever university courses on algorithms using Python that you can google out. Here's one arbitrary link.
It's also worth looking at classic textbooks, those have lots of examples.
Finally, try looking at the tutorials from certain specialized packages, such as Scipy, Turbogears, PyGame, etc.
If that's not enough, you can just go read the source code of some existing open source software. That might also help.
