'Return a Zone instance.
:param zone_id: ID of the required zone
:type  zone_id: ``str``
:rtype: :class:`Zone`'

def get_zone(self, zone_id):

    zones = self.list_zones()
    zone = [zone for zone in zones if (zone.id == zone_id)]
    if (len(zone) == 0):
        raise ZoneDoesNotExistError(driver=self, value="The    zone    doesn't    exists", zone_id=zone_id)
    return zone[0]
