How to use the jsbeautifier.jsbeautifier.core.inputscanner.InputScanner function in jsbeautifier

def unescape_string(self, s):
        # You think that a regex would work for this
        # return s.replace(/\\x([0-9a-f]{2})/gi, function(match, val) {
        #         return String.fromCharCode(parseInt(val, 16));
        #     })
        # However, dealing with '\xff', '\\xff', '\\\xff' makes this more fun.
        out = self.acorn.six.u('')
        escaped = 0

        input_scan = InputScanner(s)
        matched = None

        while input_scan.hasNext():
            # Keep any whitespace, non-slash characters
            # also keep slash pairs.
            matched = input_scan.match(re.compile(r'([\s]|[^\\]|\\\\)+'))

            if matched:
                out += matched.group(0)

            if input_scan.peek() != '\\':
                continue

            input_scan.next()
            if input_scan.peek() == 'x':
                matched = input_scan.match(re.compile(r'x([0-9A-Fa-f]{2})'))