'Return a Subnetwork object from the JSON-response dictionary.
:param  subnetwork: The dictionary describing the subnetwork.
:type   subnetwork: ``dict``
:return: Subnetwork object
:rtype: :class:`GCESubnetwork`'

def _to_subnetwork(self, subnetwork):

    extra = {}
    extra['creationTimestamp'] = subnetwork.get('creationTimestamp')
    extra['description'] = subnetwork.get('description')
    extra['gatewayAddress'] = subnetwork.get('gatewayAddress')
    extra['ipCidrRange'] = subnetwork.get('ipCidrRange')
    extra['network'] = subnetwork.get('network')
    extra['region'] = subnetwork.get('region')
    extra['selfLink'] = subnetwork.get('selfLink')
    network = self._get_object_by_kind(subnetwork.get('network'))
    region = self._get_object_by_kind(subnetwork.get('region'))
    return GCESubnetwork(id=subnetwork['id'], name=subnetwork['name'], cidr=subnetwork.get('ipCidrRange'), network=network, region=region, driver=self, extra=extra)
