code: def clear_thumbnails(self):
          '''clear all thumbnails from the map'''
          state = self.state
          for l in state.layers:
              keys = state.layers[l].keys()[:]
              for key in keys:
                  if (isinstance(state.layers[l][key], SlipThumbnail)
                      and not isinstance(state.layers[l][key], SlipIcon)):
                      state.layers[l].pop(keyf clear_thumbnails(self):
          '''clear all thumbnails from the map'''
          state = self.state
          for l in state.layers:
              keys = state.layers[l].keys()[:]
              for key in keys:
                  if (isinstance(state.layers[l][key], SlipThumbnail)
                      and not isinstance(state.layers[l][key], SlipIcon)):
                      state.layers[l].pop(key)
docs: clear all thumbnails from the map