code: func (d *Distribution) Add(sample float64) {
  	i := d.b.Bucket(sample)
  	if i >= len(d.buckets) {
  		d.buckets = append(d.buckets, make([]int64, i-len(d.buckets)+1)...)
  	}
  	d.buckets[i]++
  	d.sum += sample
  	d.count++
  	if i > d.lastNonZeroBucket {
  		d.lastNonZeroBucket = i
  	}
  }
docs: // Add adds the sample to the distribution and updates the statistics.