Mustache.js - display key instead of value

Question

I am using this data here: http://pastie.org/3231052 - How can I display the key instead of the value using Mustache or Handlebars?

[{"interval":"2012-01-21",
  "advertiser":"Advertisers 1",
  "offer":"Life Insurance",
  "cost_type":"CPA",
  "revenue_type":"CPA",
  ... etc ...
}]