code: def test_dlsim_2(self):
      # Make sure input with single-dimension doesn't raise error
      signal.dlsim((1, 2, 3), 4)
  
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 2 for calling the TestDLTI obj's underlying member method code with example usage: obj.test_dlsim_2() without return types