code: func stringLexer(quoteChar rune) stateFn {
  	// the quote char has already been read.
  	return func(l *lexer) stateFn {
  		for {
  			switch l.next() {
  			case eof:
  				l.errorf("unexpected eof while scanning string")
  			case '\\':
  				l.next() // skip escape sequences
  			case quoteChar:
  				l.emit(itemString)
  				return lexInsideTag
  			}
  		}
  	}
  }
docs: // stringLexer returns a stateFn that lexes strings surrounded by the given quote character.