code: def insert_picture(self, image_file):
          
          pic = self._new_placeholder_pic(image_file)
          self._replace_placeholder_with(pic)
          return PlaceholderPicture(pic, self._parent)
docs: Return a |PlaceholderPicture| object depicting the image in
          *image_file*, which may be either a path (string) or a file-like
          object. The image is cropped to fill the entire space of the
          placeholder. A |PlaceholderPicture| object has all the properties and
          methods of a |Picture| shape except that the value of its
          :attr:`~._BaseSlidePlaceholder.shape_type` property is
          `MSO_SHAPE_TYPE.PLACEHOLDER` instead of `MSO_SHAPE_TYPE.PICTURE`.