class_docstr: Aroon technical indicator.
  https://www.fidelity.com/learning-center/trading-investing/technical-analysis/technical-indicator-guide/aroon-indicator
  
  **Defaults Inputs:** :data:`zipline.pipeline.data.EquityPricing.low`,                          :data:`zipline.pipeline.data.EquityPricing.high`
  
  Parameters
  ----------
  window_length : int > 0
      Length of the lookback window over which to compute the Aroon
      indicator.
code: def compute(self, today, assets, out, lows, highs):
      wl = self.window_length
      high_date_index = nanargmax(highs, axis=0)
      low_date_index = nanargmin(lows, axis=0)
      evaluate(
          "(100 * high_date_index) / (wl - 1)",
          local_dict={
              "high_date_index": high_date_index,
              "wl": wl,
          },
          out=out.up,
      )
      evaluate(
          "(100 * low_date_index) / (wl - 1)",
          local_dict={
              "low_date_index": low_date_index,
              "wl": wl,
          },
          out=out.down,
      )
  
imports: from __future__ import division
  from numpy import abs, average, clip, diff, dstack, inf
  from numexpr import evaluate
  from zipline.pipeline.data import EquityPricing
  from zipline.pipeline.factors import CustomFactor
  from zipline.pipeline.mixins import SingleInputMixin
  from zipline.utils.input_validation import expect_bounded
  from zipline.utils.math_utils import nanargmax, nanargmin, nanmax, nanmean, nanstd, nanmin
  from zipline.utils.numpy_utils import rolling_window
  from .basic import exponential_weights
  from .basic import LinearWeightedMovingAverage, MaxDrawdown, SimpleMovingAverage, VWAP, WeightedAverageValue
label_desc: Use image node_id 1 for calling the Aroon obj's underlying member method code with example usage: obj.compute(today, assets, out, lows, highs) without return types