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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 _discretize(a):
 """Discretizes array values to class labels."""

  arr = np.asarray(a)
  index = np.argsort(arr)
  inverse_index = np.zeros(arr.size, dtype=np.intp)
  inverse_index[index] = np.arange(arr.size, dtype=np.intp)
  arr = arr[index]
  obs = np.r_[True, arr[1:] != arr[:-1]]
  return obs.cumsum()[inverse_index] - 1