docs: def create_hdf5(output_filename, feature_count, data):
      """
      Create a HDF5 feature files.
  
      Parameters
      ----------
      output_filename : string
          name of the HDF5 file that will be created
      feature_count : int
          dimension of all features combined
      data : list of tuples
          list of (x, y) tuples, where x is the feature vector of dimension
          ``feature_count`` and y is a label.
      """
      import h5py
      logging.info("Start creating of %s hdf file", output_filename)
      x = []
      y = []
      for features, label in data:
          assert len(features) == feature_count, \
              "Expected %i features, got %i features" % \
              (feature_count, len(features))
          x.append(features)
          y.append(int(label))
      Wfile = h5py.File(output_filename, 'w')
      Wfile.create_dataset("data", data=x, dtype='float32')
      Wfile.create_dataset("labels", data=y, dtype='int32')
      Wfile.close()