How to use the multidict._multidict_py.CIMultiDictProxy function in multidict

    + [(PyMultiDictProxy, PyMultiDict), (PyCIMultiDictProxy, PyCIMultiDict)],
    ids=(["MultiDictProxy", "CIMultiDictProxy"] if USE_CYTHON else [])
    + ["PyMultiDictProxy", "PyCIMultiDictProxy"],
)
def proxy_classes(request):
    return request.param

    + [(PyMultiDictProxy, PyMultiDict), (PyCIMultiDictProxy, PyCIMultiDict)],
    ids=(["MultiDictProxy", "CIMultiDictProxy"] if USE_CYTHON else [])
    + ["PyMultiDictProxy", "PyCIMultiDictProxy"],
)
def proxy_classes(request):
    return request.param

    + [(PyMultiDictProxy, PyMultiDict), (PyCIMultiDictProxy, PyCIMultiDict)],
    ids=(["MultiDictProxy", "CIMultiDictProxy"] if USE_CYTHON else [])
    + ["PyMultiDictProxy", "PyCIMultiDictProxy"],
)
def proxy_classes(request):
    return request.param

def __init__(self, arg):
        if not isinstance(arg, (CIMultiDict, CIMultiDictProxy)):
            raise TypeError(
                "ctor requires CIMultiDict or CIMultiDictProxy instance"
                ", not {}".format(type(arg))
            )

        self._impl = arg._impl