code: def create_noise(hop_s):
      return np.random.rand(hop_s).astype(float_type) * 2.0 - 1.0
  
imports: from numpy.testing import TestCase, assert_equal, assert_array_less
  from _tools import parametrize, skipTest
  from aubio import fvec, cvec, pvoc, float_type
  import numpy
label_desc: Use image node_id 2 for calling a global function with example usage: create_noise(hop_s) and returns: unknown