code: def test_dtype(self, xp, scp):
      imp1 = scp.signal.unit_impulse(7)
      imp2 = scp.signal.unit_impulse(5, 3, dtype=int)
      imp3 = scp.signal.unit_impulse((5, 2), (3, 1), dtype=complex)
      return imp1, imp2, imp3
  
imports: import pytest
  import cupy
  from cupy import testing
  import cupyx.scipy.signal
  import numpy
label_desc: Use image node_id 4 for calling the TestUnitImpulse obj's underlying member method code with example usage: obj.test_dtype(xp, scp) and returns: imp1,  imp2,  imp3