code: def test_complex(self, method):
      points, values = self._get_sample_4d_3()
      values = values - 2j * values
      sample = cp.asarray(
          [
              [0.1, 0.1, 1.0, 0.9],
              [0.2, 0.1, 0.45, 0.8],
              [0.5, 0.5, 0.5, 0.5],
          ]
      )
  
      interp = RegularGridInterpolator(points, values, method=method)
      rinterp = RegularGridInterpolator(
          points, values.real, method=method
      )
      iinterp = RegularGridInterpolator(
          points, values.imag, method=method
      )
  
      v1 = interp(sample)
      v2 = rinterp(sample) + 1j * iinterp(sample)
      assert_allclose(v1, v2)
  
imports: import pytest
  import cupy
  from cupy.testing import assert_allclose, assert_array_equal, assert_array_almost_equal
  from cupy_backends.cuda.api import runtime
  from pytest import raises
  from cupyx.scipy.interpolate import RegularGridInterpolator, interpn
label_desc: Use image node_id 5 for calling the TestRegularGridInterpolator obj's underlying member method code with example usage: obj.test_complex(method) without return types