Returns an instance of :attr:`~policy_class`.

        :return: An instance of the current policy class.
        :rtype: dockermap.map.policy.base.BasePolicy

def get_policy(self):
        """
        Returns an instance of :attr:`~policy_class`.

        :return: An instance of the current policy class.
        :rtype: dockermap.map.policy.base.BasePolicy
        """
        if not self._policy:
            self._policy = self.policy_class(self._maps, self._clients)
        return self._policy