code: func NewBucketer(width, growthFactor float64, numFiniteBuckets int) *Bucketer {
  	b := &Bucketer{
  		width:            width,
  		growthFactor:     growthFactor,
  		numFiniteBuckets: numFiniteBuckets,
  	}
  	b.init()
  	return b
  }
docs: // NewBucketer creates a bucketer from custom parameters.