code: def solid(self):
          
          solidFill = self._xPr.get_or_change_to_solidFill()
          self._fill = _SolidFill(solidFill)
docs: Sets the fill type to solid, i.e. a solid color. Note that calling
          this method does not set a color or by itself cause the shape to
          appear with a solid color fill; rather it enables subsequent
          assignments to properties like fore_color to set the color.