pdfCanvas referenced before assignment

[Streep]

The variable pdfCanvas is referenced before it is assigned. The only occurrence is in the function snbToPdf. Not sure how it could ever work like this for this reason, or that I am missing something.

Also, a Python 3 version would be nice. If you fix the above I can make a PR.

[ohadcn]

I do no longer have SNB, so this project is not maintained any more.

I took a quick look at what you have pointed at - does your file have empty pages? I only see how it could happen in empty pages where the loop in line 124 is never called