message: add note to modify
diff: @@ -1691,6 +1691,9 @@ where
  &mut self.indices[..],
  &mut self.data[..],
  );
  + // This is safe as long as we do the check, if we panic
  + // the structure can not be retrieved, as &mut self can not pass
  + // safely across an unwind boundary
  self.check_compressed_structure().unwrap();
  }
  }
  