On Sun, Sep 5, 2010 at 4:17 PM, Roelof Wobben <rwobben at hotmail.com> wrote: > I understand the error message. > I follow this example in the book : > http://openbookproject.net/thinkcs/python/english2e/ch11.html > And there element is not defined. It is: for element in nested_num_list: -- André Engels, andreengels at gmail.com