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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 init_poolmanager(self, connections, maxsize, block=DEFAULT_POOLBLOCK, **pool_kwargs):
 """Initializes a urllib3 PoolManager. This method should not be called from user code, and is only exposed for use when subclassing the :class:`HTTPAdapter <requests.adapters.HTTPAdapter>`. :param connections: The number of urllib3 connection pools to cache. :param maxsize: The maximum number of connections to save in the pool. :param block: Block when no free connections are available. :param pool_kwargs: Extra keyword arguments used to initialize the Pool Manager. """

        # save these values for pickling
        self._pool_connections = connections
        self._pool_maxsize = maxsize
        self._pool_block = block

        self.poolmanager = PoolManager(num_pools=connections, maxsize=maxsize,
                                       block=block, strict=True, **pool_kwargs)