code: def holtWintersAberration(requestContext, seriesList, delta=3):
      
      results = []
      for series in seriesList:
          confidenceBands = holtWintersConfidenceBands(requestContext, [series],
                                                       delta)
          lowerBand = confidenceBands[0]
          upperBand = confidenceBands[1]
          aberration = list()
          for i, actual in enumerate(series):
              if actual is None:
                  aberration.append(0)
              elif upperBand[i] is not None and actual > upperBand[i]:
                  aberration.append(actual - upperBand[i])
              elif lowerBand[i] is not None and actual < lowerBand[i]:
                  aberration.append(actual - lowerBand[i])
              else:
                  aberration.append(0)
  
          newName = "holtWintersAberration(%s)" % series.name
          results.append(TimeSeries(newName, series.start, series.end,
                                    series.step, aberration))
      return results
docs: Performs a Holt-Winters forecast using the series as input data and plots
      the positive or negative deviation of the series data from the forecast.