code: def _np_overlap_add(stft, hop_length):
      num_frames, window_length = np.shape(stft)
      # Output length will be one complete window, plus another hop_length's
      # worth of points for each additional window.
      output_length = window_length + (num_frames - 1) * hop_length
      output = np.zeros(output_length)
      for i in range(num_frames):
          output[
              i * hop_length : i * hop_length + window_length
          ] += stft[
              i,
          ]
      return output
  
imports: import itertools
  from absl.testing import parameterized
  import numpy
  from tensorflow.python.eager import context
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import gradient_checker_v2
  from tensorflow.python.ops import gradients_impl
  from tensorflow.python.ops import math_ops
  from tensorflow.python.ops.signal import spectral_ops
  from tensorflow.python.ops.signal import window_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 5 for calling the SpectralOpsTest obj's underlying member method code with example usage: obj._np_overlap_add(stft, hop_length) and returns: output