The name parameter should just be an opera:
op = webbrowser.get('opera')
Make sure that you have installed Opera on your computer and that the opera.exe executable is in the path.
>>> import webbrowser
>>> webbrowser.get ('opera')
<webbrowser.BackgroundBrowser object at 0x02095490>
See the table of valid values for the name parameter in the documentation.
(, , , , ), :
op = webbrowser.get(r'C:\\Program Files\\Opera\\opera.exe %s')