code: func (q *QueryFeedback) CalcErrorRate() float64 {
  	expected := float64(q.Expected)
  	if q.actual == 0 {
  		if expected == 0 {
  			return 0
  		}
  		return 1
  	}
  	return math.Abs(expected-float64(q.actual)) / float64(q.actual)
  }
docs: // CalcErrorRate calculates the error rate the current QueryFeedback.