<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 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)]