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'.

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)