code: function format(str, formats) {
  	let cachedFormats = formats;
  
  	if (!Ember.isArray(cachedFormats) || arguments.length > 2) {
  		cachedFormats = new Array(arguments.length - 1);
  
  		for (let i = 1, l = arguments.length; i < l; i++) {
  			cachedFormats[i - 1] = arguments[i];
  		}
  	}
  
  	let idx = 0;
  	return str.replace(/%@([0-9]+)?/g, function(s, argIndex) {
  		argIndex = (argIndex) ? parseInt(argIndex, 10) - 1 : idx++;
  		s = cachedFormats[argIndex];
  		return (s === null) ? '(null)' : (s === undefined) ? '' : Ember.inspect(s);
  	});
  }
docs: Implement Ember.String.fmt function, to avoid depreciation warnings