code: func (b *Buckets) Set(str string) error {
  	fargs := func(c rune) bool {
  		return c == ',' || c == ';'
  	}
  	// get function
  	slice := strings.FieldsFunc(str, fargs)
  	for _, bucket := range slice {
  		bu, err := strconv.ParseFloat(bucket, 64)
  		if err != nil {
  			return err
  		}
  		*b = append(*b, bu)
  	}
  	return nil
  }
docs: // Set adds strings elem into the the parser
  // it splits str on "," and ";" and apply ParseFloat to string