code: def _cleanPictures(self):
          
  
          # Project have been deleted
          if not os.path.exists(self.path):
              return
          try:
              pictures = set(os.listdir(self.pictures_directory))
              for drawing in self._drawings.values():
                  try:
                      pictures.remove(drawing.ressource_filename)
                  except KeyError:
                      pass
  
              for pict in pictures:
                  os.remove(os.path.join(self.pictures_directory, pict))
          except OSError as e:
              log.warning(str(e))
docs: Delete unused images