We often export multiple files, some of which have a revision numbers and some of which don't have any revision number.
Files that don't have a revision number get named as follows:
100-None-Filename.pdf
But we don't want "None" in our file names. Who would? What we'd like instead is:
100-Filename.pdf
So not only do we want it to omit the revision number if that data is missing but we also want it to ditch one of the dashes too, so we don't end up with:
100--Filename.pdf