code: func Line(nums []float64) string {
  	if len(nums) == 0 {
  		return ""
  	}
  	indices := normalize(nums)
  	var sparkline bytes.Buffer
  	for _, index := range indices {
  		sparkline.WriteRune(steps[index])
  	}
  	return sparkline.String()
  }
docs: // Line generates a sparkline string from a slice of
  // float64s.