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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def find_xdb_bin(wnd, power=.5, res=1500):
 """ A not so fast way to find the x-dB cutoff frequency "bin" index. Parameters wnd: The window itself as an iterable. power: The power value (squared amplitude) where the x-dB value should lie, using ``x = dB10(power)``. res : Zero-padding factor. 1 for no zero-padding, 2 for twice the length, etc.. """

  spectrum = dB20(rfft(wnd, res * len(wnd)))
  root_at_xdb = spectrum - spectrum[0] - dB10(power)
  return next(i for i, el in enumerate(zcross(root_at_xdb)) if el) / res