code: def iter_cloneable_placeholders(self):
          
          latent_ph_types = (
              PP_PLACEHOLDER.DATE, PP_PLACEHOLDER.FOOTER,
              PP_PLACEHOLDER.SLIDE_NUMBER
          )
          for ph in self.placeholders:
              if ph.element.ph_type not in latent_ph_types:
                  yield ph
docs: Generate a reference to each layout placeholder on this slide layout
          that should be cloned to a slide when the layout is applied to that
          slide.