SystemJS Knockout JS Module Loader

boot.js

var systemJsLoader = {
        loadComponent: function (name, templateConfig, callback) {
            if (templateConfig.systemjs) {
                SystemJS.import(templateConfig.systemjs)
                    .then(function (viewModelCtor) {
                        callback({
                            createViewModel: function (params, componentInfo) {
                                return viewModelCtor.viewModel(params, componentInfo);
                            },
                            template: ko.utils.parseHtmlFragment(viewModelCtor.template)
                        });
                    })
                    .catch(function (error) {
                        callback(null);
                    });
            }
        }
    };

    ko.components.loaders.unshift(systemJsLoader);

    ko.components.register('app-view', { systemjs: 'js2/mainViewModel.js' });

hi, could you show me what goes into the file 'js2/mainViewModel.js' for this to work? Thanks.