Return an instance of the appropriate shape proxy class for *shape_elm*
    on a slide master.

def _MasterShapeFactory(shape_elm, parent):
    """
    Return an instance of the appropriate shape proxy class for *shape_elm*
    on a slide master.
    """
    tag_name = shape_elm.tag
    if tag_name == qn('p:sp') and shape_elm.has_ph_elm:
        return MasterPlaceholder(shape_elm, parent)
    return BaseShapeFactory(shape_elm, parent)