Return a newly-created blank slide part having *partname* and related
        to *slide_layout_part*.

def new(cls, partname, package, slide_layout_part):
        """
        Return a newly-created blank slide part having *partname* and related
        to *slide_layout_part*.
        """
        sld = CT_Slide.new()
        slide_part = cls(partname, CT.PML_SLIDE, sld, package)
        slide_part.relate_to(slide_layout_part, RT.SLIDE_LAYOUT)
        return slide_part