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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 close(self):
 """ close all http connections. returns a deferred that fires once they're all closed. """


        def validate_client(client):
            """
            Validate that the connection is for the current client
            :param client:
            :return:
            """
            host, port = client.addr
            parsed_url = urlparse(self._hostname)
            return host == parsed_url.hostname and port == parsed_url.port

        # read https://github.com/twisted/treq/issues/86
        # to understand the following...
        def _check_fds(_):
            fds = set(reactor.getReaders() + reactor.getReaders())
            if not [fd for fd in fds if isinstance(fd, Client) and validate_client(fd)]:
                return

            return deferLater(reactor, 0, _check_fds, None)

        pool = self._async_http_client_params["pool"]
        return pool.closeCachedConnections().addBoth(_check_fds)