'Loads per-policy config override values from proxy server conf file.
:param conf: the proxy server local conf dict
:return: a dict mapping :class:`BaseStoragePolicy` to an instance of
:class:`ProxyOverrideOptions` that has policy-specific config
attributes'

def _load_per_policy_config(self, conf):

    default_options = self._make_policy_override(None, conf, {})
    overrides = defaultdict((lambda : default_options))
    overrides[None] = default_options
    for (index, override_conf) in conf.get('policy_config', {}).items():
        try:
            index = int(index)
        except ValueError:
            raise ValueError(('Override    config    must    refer    to    policy    index:    %r' % index))
        try:
            policy = POLICIES[index]
        except KeyError:
            raise ValueError(('No    policy    found    for    override    config,    index:    %s' % index))
        override = self._make_policy_override(policy, conf, override_conf)
        overrides[policy] = override
    return overrides
