How Can I create a simple widget in odoo10

How Can I create a simple widget in odoo10?? Corresponding code for following in odoo10? HOw can i convert this code to odoo10?

    local.HomePage = instance.Widget.extend({
        start: function() {
        this.$el.append("<div>Hello dear Odoo user!</div>");
        var greeting = new local.GreetingsWidget(this);
       return greeting.appendTo(this.$el);
    },
   });