code: def set_thumbnail(self, thumbnail):
          '''Sets the listitem's thumbnail image'''
          self._thumbnail = thumbnail
          return self._listitem.setThumbnailImage(thumbnailf set_thumbnail(self, thumbnail):
          '''Sets the listitem's thumbnail image'''
          self._thumbnail = thumbnail
          return self._listitem.setThumbnailImage(thumbnail)
docs: Sets the listitem's thumbnail image