code: func (tr Ranges) String() string {
  	var buf bytes.Buffer
  	buf.WriteString("[")
  	if tr.sortedRanges != nil {
  		for e := tr.sortedRanges.Front(); e != nil; e = e.Next() {
  			buf.WriteString(e.Value.(Range).String())
  			if e.Next() != nil {
  				buf.WriteString(",")
  			}
  		}
  	}
  	buf.WriteString("]")
  	return buf.String()
  }
docs: // String returns the string representation of the range.