code: def normalize(self, window=[]):
      if window is None:
          return None
      sum_win = sum(window)
      return [2.0 * i / sum_win for i in window]
  
file_path: essentia/test/src/unittests/standard/test_windowing.py
imports: from essentia_test import *
  import math
label_desc: Use image node_id 4 for calling the TestWindowing obj's underlying member method code with example usage: obj.normalize(window) and returns: unknown, None