code: def test_dlti_instantiation(self):
      # Test that lti can be instantiated.
  
      dt = 0.05
      # TransferFunction
      s = signal.dlti([1], [-1], dt=dt)
      assert isinstance(s, signal.TransferFunction)
      assert isinstance(s, signal.dlti)
      assert not isinstance(s, signal.lti)
      assert s.dt == dt
  
      # ZerosPolesGain
      s = signal.dlti(cupy.array([]), cupy.array([-1]), 1, dt=dt)
      assert isinstance(s, signal.ZerosPolesGain)
      assert isinstance(s, signal.dlti)
      assert not isinstance(s, signal.lti)
      assert s.dt == dt
  
      # StateSpace
      s = signal.dlti([1], [-1], 1, 3, dt=dt)
      assert isinstance(s, signal.StateSpace)
      assert isinstance(s, signal.dlti)
      assert not isinstance(s, signal.lti)
      assert s.dt == dt
  
      # Number of inputs
      assert_raises(ValueError, signal.dlti, 1)
      assert_raises(ValueError, signal.dlti, 1, 1, 1, 1, 1)
  
imports: from math import sqrt, pi
  from pytest import raises
  import cupy
  from cupy import testing
  import cupyx.scipy.signal
label_desc: Use image node_id 1 for calling the TestDlti obj's underlying member method code with example usage: obj.test_dlti_instantiation() without return types