'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.'

def init_poolmanager(self, connections, maxsize):

    self._pool_connections = connections
    self._pool_maxsize = maxsize
    self.poolmanager = PoolManager(num_pools=connections, maxsize=maxsize)
