code: def changeGroupImageLocal(self, image_path, thread_id=None):
          
          with get_files_from_paths([image_path]) as files:
              (image_id, mimetype), = self._upload(files)
  
          return self._changeGroupImage(image_id, thread_id)
docs: Changes a thread image from a local path
  
          :param image_path: Path of an image to upload and change
          :param thread_id: User/Group ID to change image. See :ref:`intro_threads`
          :raises: FBchatException if request failed