docs: def save(self, hdf5):
      """Saves this cascade into the given HDF5 file.
  
      **Parameters:**
  
      ``hdf5`` : :py:class:`bob.io.base.HDF5File`
        An HDF5 file open for writing
      """
      # write the cascade to file
      hdf5.set("Thresholds", self.thresholds)
      for i in range(len(self.cascade)):
        hdf5.create_group("Classifier_%d" % (i+1))
        hdf5.cd("Classifier_%d" % (i+1))
        self.cascade[i].save(hdf5)
        hdf5.cd("..")
      hdf5.create_group("FeatureExtractor")
      hdf5.cd("FeatureExtractor")
      self.extractor.save(hdf5)
      hdf5.cd("..")