code: function ( options ) {
      // Some minimal defaults
      this.defaults = {
        "locale_data" : {
          "messages" : {
            "" : {
              "domain"       : "messages",
              "lang"         : "en",
              "plural_forms" : "nplurals=2; plural=(n != 1);"
            }
            // There are no default keys, though
          }
        },
        // The default domain if one is missing
        "domain" : "messages",
        // enable debug mode to log untranslated strings to the console
        "debug" : false
      };
  
      // Mix in the sent options with the default options
      this.options = _.extend( {}, this.defaults, options );
      this.textdomain( this.options.domain );
  
      if ( options.domain && ! this.options.locale_data[ this.options.domain ] ) {
        throw new Error('Text domain set to non-existent domain: `' + options.domain + '`');
      }
    }
docs: END Miniature underscore impl Jed is a constructor function