'Initialize the state space lti/dlti system.'

def __init__(self, *system, **kwargs):

    if isinstance(system[0], LinearTimeInvariant):
        return
    super(StateSpace, self).__init__(**kwargs)
    self._A = None
    self._B = None
    self._C = None
    self._D = None
    (self.A, self.B, self.C, self.D) = abcd_normalize(*system)
