def init_poolmanager(self, connections, maxsize, block=DEFAULT_POOLBLOCK, **pool_kwargs):
<EOL>self._pool_connections = connections<EOL>self._pool_maxsize = maxsize<EOL>self._pool_block = block<EOL>self.poolmanager = PoolManager(num_pools=connections, maxsize=maxsize,<EOL>block=block, strict=True, **pool_kwargs)<EOL>
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.