def pre_process(self, xout, y0, params=()):
        """ Transforms input to internal values, used internally. """
        for pre_processor in self.pre_processors:
            xout, y0, params = pre_processor(xout, y0, params)
        return [self.numpy.atleast_1d(arr) for arr in (xout, y0, params)]
Transforms input to internal values, used internally.