On our last talk I said I want to call `__repr__` method, but this was a mistake on my side. I want to call `__str__` method actually. So using `force_str` function is a good choice. But what documentation should say there: https://github.com/chrismedrela/django/blob/gsoc2013-checks/docs/ref/checks.txt#L60? Can we say "or any other object that defines ``__str__`` method"? I'm not sure if it works on both Python 2 and 3 (in contrast to `__repr__`).