Cannot print PDF if vehicle does not supply VIN

[mgaman]

In pyOBDII.py lines 530 and on, the filename assumes that the vehicle VIN can be retrieved via the 0902 command.
In my case (1996 Saab 900) this command returns N/A
So the filename is constructed as SAVE/date..N/A.pdf which cannot be written as the second / is interpreted as a directory separator.
In my case I just commented out line 533 and added
FileName += '.pdf'

However this is not the proper solution