code: def testOne(self):
      input = [-0.5]
      envelope = Envelope(
          sampleRate=44100,
          attackTime=0,
          releaseTime=100,
          applyRectification=True,
      )(input)
      self.assertEqual(envelope[0], -input[0])
  
file_path: essentia/test/src/unittests/standard/test_envelope.py
imports: from essentia_test import *
  import numpy
label_desc: Use image node_id 4 for calling the TestEnvelope obj's underlying member method code with example usage: obj.testOne() without return types