docs: def set_pointlist(self, pointlist):
          """Overwrite pointlist.
  
          Parameters
          ----------
          pointlist : a list of strokes; each stroke is a list of points
              The inner lists represent strokes. Every stroke consists of points.
              Every point is a dictinary with 'x', 'y', 'time'.
          """
          assert type(pointlist) is list, \
              "pointlist is not of type list, but %r" % type(pointlist)
          assert len(pointlist) >= 1, \
              "The pointlist of formula_id %i is %s" % (self.formula_id,
                                                        self.get_pointlist())
          self.raw_data_json = json.dumps(pointlist)