How to use the multidict.MultiDictProxy function in multidict

def test_classes_not_abstract() -> None:
    d1 = multidict.MultiDict({"a": "b"})  # type: multidict.MultiDict[str]
    d2 = multidict.CIMultiDict({"a": "b"})  # type: multidict.CIMultiDict[str]

    d3 = multidict.MultiDictProxy(d1)
    d4 = multidict.CIMultiDictProxy(d2)

    d1.getone("a")
    d2.getall("a")
    d3.getone("a")
    d4.getall("a")

def func(data_dict=None):
        md = multidict.MultiDict(data_dict or dict())
        return multidict.MultiDictProxy(md)

def test_query_empty():
    url = URL("http://example.com")
    assert isinstance(url.query, MultiDictProxy)
    assert url.query == MultiDict()

"""Parses a MIME type into its components.

    mimetype is a MIME type string.

    Returns a MimeType object.

    Example:

    >>> parse_mimetype('text/html; charset=utf-8')
    MimeType(type='text', subtype='html', suffix='',
             parameters={'charset': 'utf-8'})

    """
    if not mimetype:
        return MimeType(type='', subtype='', suffix='',
                        parameters=MultiDictProxy(MultiDict()))

    parts = mimetype.split(';')
    params = MultiDict()  # type: MultiDict[str]
    for item in parts[1:]:
        if not item:
            continue
        key, value = cast(Tuple[str, str],
                          item.split('=', 1) if '=' in item else (item, ''))
        params.add(key.lower().strip(), value.strip(' "'))

    fulltype = parts[0].strip().lower()
    if fulltype == '*':
        fulltype = '*/*'

    mtype, stype = (cast(Tuple[str, str], fulltype.split('/', 1))
                    if '/' in fulltype else (fulltype, ''))

continue
        key, value = cast(Tuple[str, str],
                          item.split('=', 1) if '=' in item else (item, ''))
        params.add(key.lower().strip(), value.strip(' "'))

    fulltype = parts[0].strip().lower()
    if fulltype == '*':
        fulltype = '*/*'

    mtype, stype = (cast(Tuple[str, str], fulltype.split('/', 1))
                    if '/' in fulltype else (fulltype, ''))
    stype, suffix = (cast(Tuple[str, str], stype.split('+', 1))
                     if '+' in stype else (stype, ''))

    return MimeType(type=mtype, subtype=stype, suffix=suffix,
                    parameters=MultiDictProxy(params))

continue
        key, value = cast(Tuple[str, str],
                          item.split('=', 1) if '=' in item else (item, ''))
        params.add(key.lower().strip(), value.strip(' "'))

    fulltype = parts[0].strip().lower()
    if fulltype == '*':
        fulltype = '*/*'

    mtype, stype = (cast(Tuple[str, str], fulltype.split('/', 1))
                    if '/' in fulltype else (fulltype, ''))
    stype, suffix = (cast(Tuple[str, str], stype.split('+', 1))
                     if '+' in stype else (stype, ''))

    return MimeType(type=mtype, subtype=stype, suffix=suffix,
                    parameters=MultiDictProxy(params))

match = re.match(
                    r"^\s*(\S*)\s*=\s*(['\"]?)(.*?)(\2)\s*$",
                    param, re.M
                )
                if match is None:  # pragma: no cover
                    # the check exists to suppress mypy error
                    continue
                key, _, value, _ = match.groups()

                link.add(key, value)

            key = link.get("rel", url)  # type: ignore

            link.add("url", self.url.join(URL(url)))

            links.add(key, MultiDictProxy(link))

        return MultiDictProxy(links)

def update_headers(self, headers: Optional[LooseHeaders]) -> None:
        """Update request headers."""
        self.headers = CIMultiDict()  # type: CIMultiDict[str]

        # add host
        netloc = cast(str, self.url.raw_host)
        if helpers.is_ipv6_address(netloc):
            netloc = '[{}]'.format(netloc)
        if not self.url.is_default_port():
            netloc += ':' + str(self.url.port)
        self.headers[hdrs.HOST] = netloc

        if headers:
            if isinstance(headers, (dict, MultiDictProxy, MultiDict)):
                headers = headers.items()  # type: ignore

            for key, value in headers:
                # A special case for Host header
                if key.lower() == 'host':
                    self.headers[key] = value
                else:
                    self.headers.add(key, value)

def isasyncgenfunction(obj: Any) -> bool:
    func = getattr(inspect, 'isasyncgenfunction', None)
    if func is not None:
        return func(obj)
    else:
        return False


@attr.s(frozen=True, slots=True)
class MimeType:
    type = attr.ib(type=str)
    subtype = attr.ib(type=str)
    suffix = attr.ib(type=str)
    parameters = attr.ib(type=MultiDictProxy)  # type: MultiDictProxy[str]


@functools.lru_cache(maxsize=56)
def parse_mimetype(mimetype: str) -> MimeType:
    """Parses a MIME type into its components.

    mimetype is a MIME type string.

    Returns a MimeType object.

    Example:

    >>> parse_mimetype('text/html; charset=utf-8')
    MimeType(type='text', subtype='html', suffix='',
             parameters={'charset': 'utf-8'})

def get_input_validation_error(self, data_to_validate: typing.Any) -> ProcessValidationError:
        """
        Return an ProcessValidationError containing validation
        detail error for input data
        :param data_to_validate: data to use to generate validation error
        :return:
        """
        # Prevent serpyco error when Rrequest context give us a MultiDictProxy
        if isinstance(data_to_validate, (MultiDictProxy, MultiDict)):
            data_to_validate = dict(data_to_validate)

        try:
            self.serializer.load(data_to_validate)
            raise WorkflowException("Serializer should raise an exception here")
        except ValidationError as exc:
            return ProcessValidationError(
                message='Validation error of input data: "{}"'.format(exc.args[0]),
                details=exc.args[1],
                original_exception=exc,
            )
        except Exception as exc:
            self._logger.exception(
                'Unknown error during serpyco load: "{}": "{}"'.format(type(exc).__name__, str(exc))
            )
            return ProcessValidationError(