code: def test_dimpulse_4(self):
      # Raise an error for continuous-time systems
      system = signal.lti([1], [1, 1])
      assert_raises(AttributeError, signal.dimpulse, system)
  
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 15 for calling the TestDLTI obj's underlying member method code with example usage: obj.test_dimpulse_4() without return types