code: def testLnLowX(self):
      self.assertAlmostEqualVector(
          UnaryOperator(type="ln")(self.testInputLowX),
          [-69.07755, -69.07755, -69.07755, -69.07755],
      )
  
imports: from essentia_test import *
label_desc: Use image node_id 9 for calling the TestUnaryOperator obj's underlying member method code with example usage: obj.testLnLowX() without return types