I have an excel workbook that is created using an excellent \"xlsxwriter\" module. In this workbook, there about about 200 embedded charts. I am now trying to export all tho
I don't have enough reputation to comment but if you get the same issue as @R__raki__ then you can use the integer value defined by the VBA reference. For this case it would be 12.
So replace
Slide=presentation.Slides.Add(presentation.Slides.Count+1,constants.ppLayoutBlank)
with
Slide=presentation.Slides.Add(presentation.Slides.Count+1,12)
See here for more.