code: func (class *tCharClass) GetRuneAt(i int32) rune {
  	for _, r := range class.Ranges {
  		if i < r.Size {
  			return r.Start + rune(i)
  		}
  		i -= r.Size
  	}
  	panic("index out of bounds")
  }
docs: // GetRuneAt gets a rune from CharClass as a contiguous array of runes.