code: func (a *DateHistogramAggregation) ExtendedBounds(min, max interface{}) *DateHistogramAggregation {
  	a.extendedBoundsMin = min
  	a.extendedBoundsMax = max
  	return a
  }
docs: // ExtendedBounds accepts int, int64, string, or time.Time values.
  // In case the lower value in the histogram would be greater than min or the
  // upper value would be less than max, empty buckets will be generated.