Method loop_fn

tensorflow/python/eager/backprop.py:1082–1087

(i)

    self._pop_tape()

    def loop_fn(i):
      self._push_tape()
      y = array_ops.gather(target, i)
      self._pop_tape()
      return self.gradient(y, flat_sources,
                           unconnected_gradients=unconnected_gradients)

    try:
      target_size = int(target.shape[0])