code: def testRegression(self):
      inputc = [(1, -5), (2, -6), (-3, 7), (-4, 8)]
      inputc = numpy.array([complex(*c) for c in inputc], dtype="c8")
  
      expectedMag = [5.0990, 6.3246, 7.6158, 8.9443]
      expectedPhase = [-1.3734, -1.2490, 1.9757, 2.0344]
  
      c2p = CartesianToPolar()
      self.assertAlmostEqualVector(c2p(inputc)[0], expectedMag, 1e-4)
      self.assertAlmostEqualVector(c2p(inputc)[1], expectedPhase, 1e-4)
  
imports: from essentia_test import *
  from math import *
label_desc: Use image node_id 2 for calling the TestCartesianToPolar obj's underlying member method code with example usage: obj.testRegression() without return types