function NamedMap(named_map, options) {
  MapBase.call(this, options);
  this.options.pngParams.push('auth_token')
  this.options.gridParams.push('auth_token')
  this.setLayerDefinition(named_map, options)
  this.stat_tag = named_map.stat_tag;
}
adds a new sublayer to the layer with the sql and cartocss params