code: func handleEscape(s *Scanner) rune {
  	s.r.inc()
  	ch0 := s.r.peek()
  	/*
  		\" \' \\ \n \0 \b \Z \r \t ==> escape to one char
  		\% \_ ==> preserve both char
  		other ==> remove \
  	*/
  	switch ch0 {
  	case 'n':
  		ch0 = '\n'
  	case '0':
  		ch0 = 0
  	case 'b':
  		ch0 = 8
  	case 'Z':
  		ch0 = 26
  	case 'r':
  		ch0 = '\r'
  	case 't':
  		ch0 = '\t'
  	case '%', '_':
  		s.buf.WriteByte('\\')
  	}
  	return ch0
  }
docs: // handleEscape handles the case in scanString when previous char is '\'.