docs: def preprocessing(self, algorithms):
          """Apply preprocessing algorithms.
  
          Parameters
          ----------
          algorithms : a list objects
              Preprocessing allgorithms which get applied in order.
  
          Examples
          --------
          >>> import preprocessing
          >>> a = HandwrittenData(...)
          >>> preprocessing_queue = [(preprocessing.scale_and_shift, []),
          ...                        (preprocessing.connect_strokes, []),
          ...                        (preprocessing.douglas_peucker,
          ...                         {'EPSILON': 0.2}),
          ...                        (preprocessing.space_evenly,
          ...                         {'number': 100,
          ...                          'KIND': 'cubic'})]
          >>> a.preprocessing(preprocessing_queue)
          """
          assert type(algorithms) is list
          for algorithm in algorithms:
              algorithm(self)