```
$ python pwb.py nowcommons -lang:en -user:DvorapaBot -simulate
Retrieving 2 pages from wikipedia:en.
>>> File:Alaskan ADIZ.jpg <<<
Traceback (most recent call last):
File "pwb.py", line 298, in <module>
if not main():
File "pwb.py", line 293, in main
run_python_file(filename, [filename] + args, argvu, file_package)
File "pwb.py", line 96, in run_python_file
main_mod.__dict__)
File "./scripts/nowcommons.py", line 408, in <module>
main()
File "./scripts/nowcommons.py", line 404, in main
bot.run()
File "./scripts/nowcommons.py", line 273, in run
filenameOnCommons = self.findFilenameOnCommons(localImagePage)
File "./scripts/nowcommons.py", line 243, in findFilenameOnCommons
filenameOnCommons = par[par.index(':') + 1:]
ValueError: substring not found
CRITICAL: Exiting due to uncaught exception <class 'ValueError'>
```