code: def testSingle(self):
      mix = MonoMixer(type="mix")(array([(0.9, 0.5)]), 2)
      self.assertAlmostEqual(sum(mix), (0.9 + 0.5) * 0.5)
  
file_path: essentia/test/src/unittests/standard/test_monomixer.py
imports: from essentia_test import *
  from essentia import *
  from numpy import sum
label_desc: Use image node_id 5 for calling the TestMonoMixer_Streaming obj's underlying member method code with example usage: obj.testSingle() without return types