How to use the multidict.CIMultiDictProxy function in multidict

"""

    task = mock.Mock()
    if loop is ...:
        loop = mock.Mock()
        loop.create_future.return_value = ()

    if version < HttpVersion(1, 1):
        closing = True

    if headers:
        headers = CIMultiDictProxy(CIMultiDict(headers))
        raw_hdrs = tuple(
            (k.encode('utf-8'), v.encode('utf-8')) for k, v in headers.items())
    else:
        headers = CIMultiDictProxy(CIMultiDict())
        raw_hdrs = ()

    chunked = 'chunked' in headers.get(hdrs.TRANSFER_ENCODING, '').lower()

    message = RawRequestMessage(
        method, path, version, headers,
        raw_hdrs, closing, False, False, chunked, URL(path))
    if app is None:
        app = _create_app_mock()

    if transport is sentinel:
        transport = _create_transport(sslcontext)

    if protocol is sentinel:
        protocol = mock.Mock()
        protocol.transport = transport

async def start(self, connection, read_until_eof=False):
            nonlocal conn
            conn = connection
            self.status = 123
            self.reason = 'Test OK'
            self._headers = CIMultiDictProxy(CIMultiDict())
            self.cookies = SimpleCookie()
            return

async def handler(request):
        assert isinstance(request.headers, CIMultiDictProxy)
        return web.Response()

def test_base_ctor() -> None:
    message = RawRequestMessage(
        'GET', '/path/to?a=1&b=2', HttpVersion(1, 1),
        CIMultiDictProxy(CIMultiDict()), (),
        False, False, False, False, URL('/path/to?a=1&b=2'))

    req = web.BaseRequest(message,
                          mock.Mock(),
                          mock.Mock(),
                          mock.Mock(),
                          mock.Mock(),
                          mock.Mock())

    assert 'GET' == req.method
    assert HttpVersion(1, 1) == req.version
    assert req.host == socket.getfqdn()
    assert '/path/to?a=1&b=2' == req.path_qs
    assert '/path/to' == req.path
    assert 'a=1&b=2' == req.query_string
    assert CIMultiDict() == req.headers

def build_response(vcr_request, vcr_response, history):
    request_info = RequestInfo(
        url=URL(vcr_request.url),
        method=vcr_request.method,
        headers=CIMultiDictProxy(CIMultiDict(vcr_request.headers)),
        real_url=URL(vcr_request.url),
    )
    response = MockClientResponse(vcr_request.method, URL(vcr_response.get("url")), request_info=request_info)
    response.status = vcr_response["status"]["code"]
    response._body = vcr_response["body"].get("string", b"")
    response.reason = vcr_response["status"]["message"]
    response._headers = CIMultiDictProxy(CIMultiDict(vcr_response["headers"]))
    response._history = tuple(history)

    response.close()
    return response

"""

        if self._read_bytes:
            raise RuntimeError("Cannot clone request "
                               "after reading its content")

        dct = {}  # type: Dict[str, Any]
        if method is not sentinel:
            dct['method'] = method
        if rel_url is not sentinel:
            new_url = URL(rel_url)
            dct['url'] = new_url
            dct['path'] = str(new_url)
        if headers is not sentinel:
            # a copy semantic
            dct['headers'] = CIMultiDictProxy(CIMultiDict(headers))
            dct['raw_headers'] = tuple((k.encode('utf-8'), v.encode('utf-8'))
                                       for k, v in headers.items())

        message = self._message._replace(**dct)

        kwargs = {}
        if scheme is not sentinel:
            kwargs['scheme'] = scheme
        if host is not sentinel:
            kwargs['host'] = host
        if remote is not sentinel:
            kwargs['remote'] = remote

        return self.__class__(
            message,
            self._payload,

json_re = re.compile(r'^application/(?:[\w.+-]+?\+)?json')


@attr.s(frozen=True, slots=True)
class ContentDisposition:
    type = attr.ib(type=str)  # type: Optional[str]
    parameters = attr.ib(type=MappingProxyType)  # type: MappingProxyType[str, str]  # noqa
    filename = attr.ib(type=str)  # type: Optional[str]


@attr.s(frozen=True, slots=True)
class RequestInfo:
    url = attr.ib(type=URL)
    method = attr.ib(type=str)
    headers = attr.ib(type=CIMultiDictProxy)  # type: CIMultiDictProxy[str]
    real_url = attr.ib(type=URL)

    @real_url.default
    def real_url_default(self) -> URL:
        return self.url


class Fingerprint:
    HASHFUNC_BY_DIGESTLEN = {
        16: md5,
        20: sha1,
        32: sha256,
    }

    def __init__(self, fingerprint: bytes) -> None:
        digestlen = len(fingerprint)

def __init__(self, *, body: Optional[Union[bytes, str]] = None, status: int = 200, reason: Optional[str] = None, headers: Optional[Union[Dict, CIMultiDict, CIMultiDictProxy]] = None, content_type: Optional[str] = None, charset: Optional[str] = None) -> None:
        if headers is None:
            headers = CIMultiDict()
        elif not isinstance(headers, (CIMultiDict, CIMultiDictProxy)):
            headers = CIMultiDict(headers)

        self._body = body
        self._status = status
        self._reason = reason
        self._headers = headers
        self.content_type = content_type if hdrs.CONTENT_TYPE not in headers else None
        self.charset = charset if hdrs.CONTENT_TYPE not in headers else None

        self.missing_content_type = hdrs.CONTENT_TYPE not in headers and not content_type and not charset

break

                if self._continue is not None and not self._continue.done():
                    self._continue.set_result(True)
                    self._continue = None

        # payload eof handler
        payload.on_eof(self._response_eof)

        # response status
        self.version = message.version
        self.status = message.code
        self.reason = message.reason

        # headers
        self.headers = CIMultiDictProxy(message.headers)
        self.raw_headers = tuple(message.raw_headers)

        # payload
        self.content = payload

        # cookies
        for hdr in self.headers.getall(hdrs.SET_COOKIE, ()):
            try:
                self.cookies.load(hdr)
            except CookieError as exc:
                client_logger.warning(
                    'Can not load response cookies: %s', exc)
        return self