code: def zpk2ss(z, p, k):
      
      import scipy.signal
      return scipy.signal.zpk2ss(z,p,k)
docs: Zero-pole-gain representation to state-space representation
  
      :param sequence z,p: Zeros and poles.
      :param float k: System gain.
  
      :return:
          * A, B, C, D : ndarray State-space matrices.
  
      .. note:: wrapper of scipy function zpk2ss