index in #each expression (Meteor & Spacebars)

Suppose you want to write an #each expression in a Meteor.js template. And suppose that you want to print the index of an item. Something like:

{{#each steps}}

    {{index}} : {{stepDescription}}

{{/each}}

This is a legitimate need, and even available in Handlebars, using {{@index}}, as you can see in this stackoverflow thread or this issue.

Meteor does not support this option yet (0.8).  They even mentioned this issue in their wiki:

Syntax extensions. Handlebars syntax is extremely minimal, and we foresee adding some additional well-chosen extensions over time. (We will also implement the top features of current Handlebars that are missing from Meteor, like #each that supports objects and lets you access the current index or key.)

This looks promising. But for people who need a solution right now, you can just create a helper that adds an _index property to each item in the array: