code: def test_zero(self):
      # carg(-0 +- 0i) returns +- pi
      check_real_value(ncu._arg, np.NZERO, np.PZERO, np.pi, False)
      check_real_value(ncu._arg, np.NZERO, np.NZERO, -np.pi, False)
  
      # carg(+0 +- 0i) returns +- 0
      check_real_value(ncu._arg, np.PZERO, np.PZERO, np.PZERO)
      check_real_value(ncu._arg, np.PZERO, np.NZERO, np.NZERO)
  
      # carg(x +- 0i) returns +- 0 for x > 0
      check_real_value(ncu._arg, 1, np.PZERO, np.PZERO, False)
      check_real_value(ncu._arg, 1, np.NZERO, np.NZERO, False)
  
      # carg(x +- 0i) returns +- pi for x < 0
      check_real_value(ncu._arg, -1, np.PZERO, np.pi, False)
      check_real_value(ncu._arg, -1, np.NZERO, -np.pi, False)
  
      # carg(+- 0 + yi) returns pi/2 for y > 0
      check_real_value(ncu._arg, np.PZERO, 1, 0.5 * np.pi, False)
      check_real_value(ncu._arg, np.NZERO, 1, 0.5 * np.pi, False)
  
      # carg(+- 0 + yi) returns -pi/2 for y < 0
      check_real_value(ncu._arg, np.PZERO, -1, 0.5 * np.pi, False)
      check_real_value(ncu._arg, np.NZERO, -1, -0.5 * np.pi, False)
  
imports: import sys
  import platform
  import pytest
  import numpy
  import numpy.core._multiarray_umath
  from numpy.testing import assert_raises, assert_equal, assert_array_equal, assert_almost_equal, assert_array_max_ulp
label_desc: Use image node_id 2 for calling the TestCarg obj's underlying member method code with example usage: obj.test_zero() without return types