docs: def _load(self, hdf5):
      """Loads the intermediate state of the bootstrapping from file."""
      positives = set(hdf5.get("PositiveIndices"))
      negatives = set(hdf5.get("NegativeIndices"))
      hdf5.cd("Model")
      model = bob.learn.boosting.BoostedMachine(hdf5)
      return model, positives, negatives