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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def rpccall(pvname, request=None, rtype=None):
 """Decorator marks a client proxy method. :param str pvname: The PV name, which will be formated using the 'format' argument of the proxy class constructor. :param request: A pvRequest string or :py:class:`p4p.Value` passed to eg. :py:meth:`p4p.client.thread.Context.rpc`. The method to be decorated must have all keyword arguments, where the keywords are type code strings or :class:`~p4p.Type`. """

    def wrapper(fn):
        fn._call_PV = pvname
        fn._call_Request = request
        fn._reply_Type = rtype
        return fn
    return wrapper