code: def testInvalidInput(self):
      self.assertComputeFails(Flatness(), [1, 2, 4, -3, 6, 7])
  
file_path: essentia/test/src/unittests/stats/test_flatness.py
imports: from essentia_test import *
label_desc: Use image node_id 5 for calling the TestFlatness obj's underlying member method code with example usage: obj.testInvalidInput() without return types