/** Because Handlebars sucks and won't let you iterate with @index
 * Use this lookup helper to do things with the automatic @index var inside loops
 *
 * Usage example: (Get the item at @index each iteration through foo)
 * {{#each foo}}
 *   <div>{{someProp}}</div>
 *   <div>{{lookup ../dailyStat @index}}</div>
 * {{/each}}
 *
 * Block usage example: (get the item at @index in monthlyUniqueCustomers and then use its subcomponents
 * {{#lookup monthlyUniqueCustomers @index}}
 *  <div>Count: {{count}}</div>
 *  <div>Growth: {{growth}}</div>
 * {{/lookup}}
 * @param {obj} object (or array) whose field is accessed in a .hbs file
 * @param {key} key (or index) designating which field of the object to access
 * @param {options} [options] - allows the helper to be used as a block helper
 * @returns {string} The text to be generated by handlebars
 */
Handlebars.registerHelper('lookup', function(obj, key, options) {
  if (options) return options.fn(obj[key]);
  else return obj[key];
});