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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 input_diff(orig_img):
 """Average L2 difference between optimized image and orig_img. This objective is usually mutliplied by a negative number and used as a penalty in making advarsarial counterexamples. """

  def inner(T):
    diff = T("input") - orig_img
    return tf.sqrt(tf.reduce_mean(diff**2))
  return inner