How to use the waitress.compat.tostr function in waitress

def get_header_lines(header):
    """
    Splits the header into lines, putting multi-line headers together.
    """
    r = []
    lines = header.split(b"\r\n")
    for line in lines:
        if not line:
            continue

        if b"\r" in line or b"\n" in line:
            raise ParsingError('Bare CR or LF found in header line "%s"' % tostr(line))

        if line.startswith((b" ", b"\t")):
            if not r:
                # https://corte.si/posts/code/pathod/pythonservers/index.html
                raise ParsingError('Malformed header line "%s"' % tostr(line))
            r[-1] += line
        else:
            r.append(line)
    return r

def split_uri(uri):
    # urlsplit handles byte input by returning bytes on py3, so
    # scheme, netloc, path, query, and fragment are bytes
    try:
        scheme, netloc, path, query, fragment = urlparse.urlsplit(uri)
    except UnicodeError:
        raise ParsingError('Bad URI')
    return (
        tostr(scheme),
        tostr(netloc),
        unquote_bytes_to_wsgi(path),
        tostr(query),
        tostr(fragment),
    )

path, fragment = path.split(b"#", 1)

        if b"?" in path:
            path, query = path.split(b"?", 1)
    else:
        try:
            scheme, netloc, path, query, fragment = urlparse.urlsplit(uri)
        except UnicodeError:
            raise ParsingError("Bad URI")

    return (
        tostr(scheme),
        tostr(netloc),
        unquote_bytes_to_wsgi(path),
        tostr(query),
        tostr(fragment),
    )

if uri[:2] == b"//":
        path = uri

        if b"#" in path:
            path, fragment = path.split(b"#", 1)

        if b"?" in path:
            path, query = path.split(b"?", 1)
    else:
        try:
            scheme, netloc, path, query, fragment = urlparse.urlsplit(uri)
        except UnicodeError:
            raise ParsingError("Bad URI")

    return (
        tostr(scheme),
        tostr(netloc),
        unquote_bytes_to_wsgi(path),
        tostr(query),
        tostr(fragment),
    )

for line in lines:
            index = line.find(b':')
            if index > 0:
                key = line[:index]
                if b'_' in key:
                    continue
                value = line[index + 1:].strip()
                key1 = tostr(key.upper().replace(b'-', b'_'))
                # If a header already exists, we append subsequent values
                # seperated by a comma. Applications already need to handle
                # the comma seperated values, as HTTP front ends might do
                # the concatenation for you (behavior specified in RFC2616).
                try:
                    headers[key1] += tostr(b', ' + value)
                except KeyError:
                    headers[key1] = tostr(value)
            # else there's garbage in the headers?

        # command, uri, version will be bytes
        command, uri, version = crack_first_line(first_line)
        version = tostr(version)
        command = tostr(command)
        self.command = command
        self.version = version
        (self.proxy_scheme,
         self.proxy_netloc,
         self.path,
         self.query, self.fragment) = split_uri(uri)
        self.url_scheme = self.adj.url_scheme
        connection = headers.get('CONNECTION', '')

        if version == '1.0':

version = m.group(5)
        else:
            version = b""
        method = m.group(1)

        # the request methods that are currently defined are all uppercase:
        # https://www.iana.org/assignments/http-methods/http-methods.xhtml and
        # the request method is case sensitive according to
        # https://tools.ietf.org/html/rfc7231#section-4.1

        # By disallowing anything but uppercase methods we save poor
        # unsuspecting souls from sending lowercase HTTP methods to waitress
        # and having the request complete, while servers like nginx drop the
        # request onto the floor.
        if method != method.upper():
            raise ParsingError('Malformed HTTP method "%s"' % tostr(method))
        uri = m.group(2)
        return method, uri, version
    else:
        return b"", b"", b""

headers = self.headers
        for line in lines:
            index = line.find(b':')
            if index > 0:
                key = line[:index]
                if b'_' in key:
                    continue
                value = line[index + 1:].strip()
                key1 = tostr(key.upper().replace(b'-', b'_'))
                # If a header already exists, we append subsequent values
                # seperated by a comma. Applications already need to handle
                # the comma seperated values, as HTTP front ends might do
                # the concatenation for you (behavior specified in RFC2616).
                try:
                    headers[key1] += tostr(b', ' + value)
                except KeyError:
                    headers[key1] = tostr(value)
            # else there's garbage in the headers?

        # command, uri, version will be bytes
        command, uri, version = crack_first_line(first_line)
        version = tostr(version)
        command = tostr(command)
        self.command = command
        self.version = version
        (self.proxy_scheme,
         self.proxy_netloc,
         self.path,
         self.query, self.fragment) = split_uri(uri)
        self.url_scheme = self.adj.url_scheme
        connection = headers.get('CONNECTION', '')

value = line[index + 1:].strip()
                key1 = tostr(key.upper().replace(b'-', b'_'))
                # If a header already exists, we append subsequent values
                # seperated by a comma. Applications already need to handle
                # the comma seperated values, as HTTP front ends might do
                # the concatenation for you (behavior specified in RFC2616).
                try:
                    headers[key1] += tostr(b', ' + value)
                except KeyError:
                    headers[key1] = tostr(value)
            # else there's garbage in the headers?

        # command, uri, version will be bytes
        command, uri, version = crack_first_line(first_line)
        version = tostr(version)
        command = tostr(command)
        self.command = command
        self.version = version
        (self.proxy_scheme,
         self.proxy_netloc,
         self.path,
         self.query, self.fragment) = split_uri(uri)
        self.url_scheme = self.adj.url_scheme
        connection = headers.get('CONNECTION', '')

        if version == '1.0':
            if connection.lower() != 'keep-alive':
                self.connection_close = True

        if version == '1.1':
            # since the server buffers data from chunked transfers and clients
            # never need to deal with chunked requests, downstream clients