Return a newly added slide that inherits layout from *slide_layout*.

def add_slide(self, slide_layout):
        """
        Return a newly added slide that inherits layout from *slide_layout*.
        """
        rId, slide = self.part.add_slide(slide_layout)
        slide.shapes.clone_layout_placeholders(slide_layout)
        self._sldIdLst.add_sldId(rId)
        return slide