code: func (hg *Histogram) ContainsFeedback() bool {
  	for _, bkt := range hg.Buckets {
  		if bkt.Repeat == 0 {
  			return true
  		}
  	}
  	return false
  }
docs: // ContainsFeedback checks if the histogram contains feedback updates.
  // We can test it from the `repeat` field because only feedback will update it to 0.