code: func NewHistogram(n int) *NumericHistogram {
  	return &NumericHistogram{
  		bins:    make([]bin, 0),
  		maxbins: n,
  		total:   0,
  	}
  }
docs: // NewHistogram returns a new NumericHistogram with a maximum of n bins.
  //
  // There is no "optimal" bin count, but somewhere between 20 and 80 bins
  // should be sufficient.