Thank you VERY much! These other errors are not so serious. I think I'll fix them soon. The most important thing is that now I'm ready to work on that code again. Life is beautiful again!
Damn, I knew it is some very stupid mistake. I must learn how to use that pylint, instead of asking people on the web such a stupid questions. (The sad thing is that I'm the only one developer, who works on that code. I think I had just stuck before I sent the first message in this topic.) -- http://mail.python.org/mailman/listinfo/python-list
