How to use the tornado.escape.utf8 function in tornado

version = int(m.group(1))
                if version == 2:
                    _, mask, masked_token, timestamp = cookie.split("|")

                    mask = binascii.a2b_hex(utf8(mask))
                    token = _websocket_mask(
                        mask, binascii.a2b_hex(utf8(masked_token)))
                    timestamp = int(timestamp)
                    return version, token, timestamp
                else:
                    # Treat unknown versions as not present instead of failing.
                    raise Exception("Unknown xsrf cookie version")
            else:
                version = 1
                try:
                    token = binascii.a2b_hex(utf8(cookie))
                except (binascii.Error, TypeError):
                    token = utf8(cookie)
                # We don't have a usable timestamp in older versions.
                timestamp = int(time.time())
                return (version, token, timestamp)
        except Exception:
            # Catch exceptions and return nothing instead of failing.
            gen_log.debug("Uncaught exception in _decode_xsrf_token",
                          exc_info=True)
            return None, None, None

"""Parses the hpack static table, which was copied from
    http://http2.github.io/http2-spec/compression.html#static.table
    corresponding to
    http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-12#appendix-A
    """
    # start the table with a dummy entry 0
    table = [None]
    with open(os.path.join(os.path.dirname(__file__),
                           'hpack_static_table.txt')) as f:
        for line in f:
            if not line:
                continue
            fields = line.split('\t')
            if int(fields[0]) != len(table):
                raise ValueError("inconsistent numbering in static table")
            name = utf8(fields[1].strip())
            value = utf8(fields[2].strip()) if len(fields) > 2 else None
            table.append((name, value))
    static_keys = {}
    static_pairs = {}
    for i, pair in enumerate(table):
        if pair is None:
            continue
        if pair[0] not in static_keys:
            # For repeated keys, prefer the earlier one.
            static_keys[pair[0]] = i
        static_pairs[pair] = i
    return table, static_keys, static_pairs

if not data: raise Exception("WSGI app did not call start_response")

        status_code = int(data["status"].split()[0])
        headers = data["headers"]
        header_set = set(k.lower() for (k,v) in headers)
        body = escape.utf8(body)
        if "content-length" not in header_set:
            headers.append(("Content-Length", str(len(body))))
        if "content-type" not in header_set:
            headers.append(("Content-Type", "text/html; charset=UTF-8"))
        if "server" not in header_set:
            headers.append(("Server", "TornadoServer/%s" % tornado.version))

        parts = [escape.utf8("HTTP/1.1 " + data["status"] + "\r\n")]
        for key, value in headers:
            parts.append(escape.utf8(key) + b(": ") + escape.utf8(value) + b("\r\n"))
        parts.append(b("\r\n"))
        parts.append(body)
        request.write(b("").join(parts))
        request.finish()
        self._log(status_code, request)

def write_message(self, message, binary=False):
        """Sends the given message to the client of this Web Socket."""
        if binary:
            opcode = 0x2
        else:
            opcode = 0x1
        message = tornado.escape.utf8(message)
        assert isinstance(message, bytes_type)

        if not self._started:
            self._pending_messages.append(message)
        else:
            self._write_frame(True, opcode, message)

def compute_accept_value(key):
        """Computes the value for the Sec-WebSocket-Accept header,
        given the value for Sec-WebSocket-Key.
        """
        sha1 = hashlib.sha1()
        sha1.update(utf8(key))
        sha1.update(b"258EAFA5-E914-47DA-95CA-C5AB0DC85B11")  # Magic value
        return native_str(base64.b64encode(sha1.digest()))

def decode_signed_value(secret, name, value, max_age_days=31, clock=None, min_version=None):
    if clock is None:
        clock = time.time
    if min_version is None:
        min_version = DEFAULT_SIGNED_VALUE_MIN_VERSION
    if min_version > 2:
        raise ValueError("Unsupported min_version %d" % min_version)
    if not value:
        return None

    # Figure out what version this is.  Version 1 did not include an
    # explicit version field and started with arbitrary base64 data,
    # which makes this tricky.
    value = utf8(value)
    m = _signed_value_version_re.match(value)
    if m is None:
        version = 1
    else:
        try:
            version = int(m.group(1))
            if version > 999:
                # Certain payloads from the version-less v1 format may
                # be parsed as valid integers.  Due to base64 padding
                # restrictions, this can only happen for numbers whose
                # length is a multiple of 4, so we can treat all
                # numbers up to 999 as versions, and for the rest we
                # fall back to v1 format.
                version = 1
        except ValueError:
            version = 1

If the ``status`` argument is specified, that value is used as the
        HTTP status code; otherwise either 301 (permanent) or 302
        (temporary) is chosen based on the ``permanent`` argument.
        The default is 302 (temporary).
        """
        if self._headers_written:
            raise Exception("Cannot redirect after headers have been written")
        if status is None:
            status = 301 if permanent else 302
        else:
            assert isinstance(status, int) and 300 <= status <= 399
        self.set_status(status)
        # Remove whitespace
        url = re.sub(b(r"[\x00-\x20]+"), "", utf8(url))
        self.set_header("Location", urlparse.urljoin(utf8(self.request.uri),
                                                     url))
        self.finish()

Returns ``True`` if the request's Etag matches and a 304 should be
        returned. For example::

            self.set_etag_header()
            if self.check_etag_header():
                self.set_status(304)
                return

        This method is called automatically when the request is finished,
        but may be called earlier for applications that override
        `compute_etag` and want to do an early check for ``If-None-Match``
        before completing the request.  The ``Etag`` header should be set
        (perhaps with `set_etag_header`) before calling this method.
        """
        etag = self._headers.get("Etag")
        inm = utf8(self.request.headers.get("If-None-Match", ""))
        return bool(etag and inm and inm.find(etag) >= 0)

if isinstance(file_part, (unicode_type, bytes_type)):
                    js_files.append(file_part)
                else:
                    js_files.extend(file_part)
            embed_part = module.embedded_css()
            if embed_part:
                css_embed.append(utf8(embed_part))
            file_part = module.css_files()
            if file_part:
                if isinstance(file_part, (unicode_type, bytes_type)):
                    css_files.append(file_part)
                else:
                    css_files.extend(file_part)
            head_part = module.html_head()
            if head_part:
                html_heads.append(utf8(head_part))
            body_part = module.html_body()
            if body_part:
                html_bodies.append(utf8(body_part))

        def is_absolute(path):
            return any(path.startswith(x) for x in ["/", "http:", "https:"])
        if js_files:
            # Maintain order of JavaScript files given by modules
            paths = []
            unique_paths = set()
            for path in js_files:
                if not is_absolute(path):
                    path = self.static_url(path)
                if path not in unique_paths:
                    paths.append(path)
                    unique_paths.add(path)

css_files = []
        html_heads = []
        html_bodies = []
        for module in getattr(self, "_active_modules", {}).values():
            embed_part = module.embedded_javascript()
            if embed_part:
                js_embed.append(utf8(embed_part))
            file_part = module.javascript_files()
            if file_part:
                if isinstance(file_part, (unicode_type, bytes)):
                    js_files.append(file_part)
                else:
                    js_files.extend(file_part)
            embed_part = module.embedded_css()
            if embed_part:
                css_embed.append(utf8(embed_part))
            file_part = module.css_files()
            if file_part:
                if isinstance(file_part, (unicode_type, bytes)):
                    css_files.append(file_part)
                else:
                    css_files.extend(file_part)
            head_part = module.html_head()
            if head_part:
                html_heads.append(utf8(head_part))
            body_part = module.html_body()
            if body_part:
                html_bodies.append(utf8(body_part))

        if js_files:
            # Maintain order of JavaScript files given by modules
            js = self.render_linked_js(js_files)