docs: function ownCustomObject(name, Meta) {
      var key = memberProperty(name);
      var capitalized = capitalize(name);
      Meta.prototype['writable' + capitalized] = function (create) {
        var ret = this[key];
        if (!ret) {
          ret = this[key] = create(this.source);
        }
        return ret;
      };
      Meta.prototype['readable' + capitalized] = function () {
        return this[key];
      };
    }