code: function(zone, callback) {
      var self = this,
          zoneId = zone instanceof dns.Zone ? zone.id : zone;
  
      var requestOptions = {
        path: urlJoin(_urlPrefix, zoneId, 'subdomains'),
        method: 'GET'
      };
  
      self._request(requestOptions, function(err, body, res) {
        return err
          ? callback(err)
          : callback(null, body.domains.map(function (result) {
          return new dns.Zone(self, result);
        }), res);
      });
    }
docs: @name Client.getSubZones
  @description gets a list of the subzones for a provided zone
  
  @param {object|Number}     zone          the zone of the record to query for
  @param {Function}          callback      handles the callback of your api call