code: function PriorityListItem (key, value, priority, serial) {
              var _priority,
                  _serial,
                  contextName = 'sjl.stdlib.PriorityListItem';
              /**
               * Key name.  Set on construction.
               * @member sjl.stdlib.PriorityListItem#key {String}
               * @readonly
               */
              /**
               * Value name.  Set on construction.
               * @member sjl.stdlib.PriorityListItem#value {*}
               * @readonly
               */
              /**
               * Serial index.
               * @member sjl.stdlib.PriorityListItem#serial {Number}
               * @readonly
               */
              /**
               * Priority.
               * @member sjl.stdlib.PriorityListItem#priority {Number}
               * @readonly
               */
              Object.defineProperties(this, {
                  key: {
                      value: key,
                      enumerable: true
                  },
                  serial: {
                      get: function () {
                          return _serial;
                      },
                      set: function (value) {
                          sjl.throwTypeErrorIfNotOfType(contextName, 'serial', value, Number);
                          _serial = value;
                      },
                      enumerable: true
                  },
                  value: {
                      value: value,
                      enumerable: true
                  },
                  priority: {
                      get: function () {
                          return _priority;
                      },
                      set: function (value) {
                          sjl.throwTypeErrorIfNotOfType(contextName, 'priority', value, Number);
                          _priority = value;
                      },
                      enumerable: true
                  }
              });
              this.priority = priority;
              this.serial = serial;
          }
docs: Priority List Item Constructor (internal docblock).
  @constructor
  @param key {*}
  @param value {*}
  @param priority {Number}
  @param serial {Number}
  @private