code: func (bj BinaryJSON) Unquote() (string, error) {
  	switch bj.TypeCode {
  	case TypeCodeString:
  		tmp := string(hack.String(bj.GetString()))
  		s, err := unquoteString(tmp)
  		if err != nil {
  			return "", errors.Trace(err)
  		}
  		// Remove prefix and suffix '"'.
  		slen := len(s)
  		if slen > 1 {
  			head, tail := s[0], s[slen-1]
  			if head == '"' && tail == '"' {
  				return s[1 : slen-1], nil
  			}
  		}
  		return s, nil
  	default:
  		return bj.String(), nil
  	}
  }
docs: // Unquote is for JSON_UNQUOTE.