code: def test_corner_cases(self):
      feat_sync = self.processor([np.arange(100), np.array([])])
      self.assertTrue(np.allclose(feat_sync, [[], []]))
      feat_sync = self.processor(
          [np.arange(100), np.array([0, 0.5, 1.5])]
      )
      self.assertTrue(np.allclose(feat_sync, [[[11.0], [33.5]]]))
  
imports: from __future__ import absolute_import, division, print_function
  import unittest
  from os.path import join
  from madmom.ml.hmm import HiddenMarkovModel
  from madmom.audio.chroma import CLPChroma
  from madmom.features import Activations
  from madmom.features.downbeats import *
  from madmom.models import PATTERNS_BALLROOM
  from .None import ACTIVATIONS_PATH, ANNOTATIONS_PATH, AUDIO_PATH, DETECTIONS_PATH
  from .test_utils import DETECTION_FILES
label_desc: Use image node_id 3 for calling the TestSyncronizeFeaturesProcessorClass obj's underlying member method code with example usage: obj.test_corner_cases() without return types