code: def rename_slide_parts(self, rIds):
          
          for idx, rId in enumerate(rIds):
              slide_part = self.related_parts[rId]
              slide_part.partname = PackURI(
                  '/ppt/slides/slide%d.xml' % (idx+1)
              )
docs: Assign incrementing partnames like ``/ppt/slides/slide9.xml`` to the
          slide parts identified by *rIds*, in the order their id appears in
          that sequence. The name portion is always ``slide``. The number part
          forms a continuous sequence starting at 1 (e.g. 1, 2, ... 10, ...).
          The extension is always ``.xml``.