How to access outer {{#each}} collection value in the nested loop

What is the standard way to access outer #each collection values in the loop? for example:

<template name="example">
  {{#each outerCollection}}
  <tr>
    {{#each innerCollection}}
      <td>{{aaa}}</td>
    {{/each}}
  </tr>
  {{/each}}
</template>

Template.example.aaa = function(){
  // cannot access outerCollection values
}

in above Template.example.aaa, this points to the inner collection.

I cannot find way to access outerCollection items. My solution is like below, I am defining my own helper function. Is it a standard Meteor way to achieve this purpose?

<template name="example">
  {{#each outerCollection}}
  <tr>
    {{#each innerCollection}}
      <td>{{myHelper ../outerItem innerItem}}</td>
    {{/each}}
  </tr>
  {{/each}}
</template>

Handlebars.registerHelper('myHelper', function (outItem, inItem) {
  // can access outerCollection via outerItem
});

I found a similar question for the case of inner event handler access.