code: def test_py_c_diff(self):
      # Test _Py_c_diff()
      _py_c_diff = _testcapi._py_c_diff
  
      self.assertEqual(_py_c_diff(1, 1j), (1 - 1j, 0))
  
imports: from math import isnan
  import errno
  import unittest
  import warnings
  from test.test_capi.test_getargs import BadComplex, BadComplex2, Complex, FloatSubclass, Float, BadFloat, BadFloat2, ComplexSubclass
  from test.support import import_helper
label_desc: Use image node_id 9 for calling the CAPIComplexTest obj's underlying member method code with example usage: obj.test_py_c_diff() without return types