code: def test_group_poles(self):
      _group_poles = cupyx.scipy.signal.unique_roots
  
      unique, multiplicity = _group_poles(
          cupy.asarray([1.0, 1.001, 1.003, 2.0, 2.003, 3.0]), 0.1, "min"
      )
      testing.assert_allclose(unique, [1.0, 2.0, 3.0], atol=1e-15)
      testing.assert_allclose(multiplicity, [3, 2, 1], atol=1e-15)
  
imports: import numpy
  import pytest
  import cupy
  from cupy import testing
  import cupyx.scipy.signal
label_desc: Use image node_id 2 for calling the TestPartialFractionExpansion obj's underlying member method code with example usage: obj.test_group_poles() without return types