Updating an Ember Handlebars Helper to Current Syntax

I'm pretty new to Ember and still trying to get a solid grasp of how everything ties in together. That said, I've pieced together some functionality based on an old example but want to gain a better understanding of helpers and how to work with them.

Here is my original helper:

Ember.Handlebars.helper('autocomplete', Ember.View.extend({
    templateName: 'controls/autocomplete',

    filteredList: function() {
        ...

        return list.filter(function(item) {
            ...
        });
    }.property('list.@each', 'filter')
}));

When I try updating my version of Ember I get the following error: Uncaught TypeError: Cannot read property 'isHelperFactory' of undefined

Could somebody help me gain a better understanding of helpers, and also help with me getting this updated? Thanks!

I can toss everything onto a CodePen if need be