function padNumber(num, digits, trim, negWrap) {
  var neg = '';
  if (num < 0 || (negWrap && num <= 0)) {
    if (negWrap) {
      num = -num + 1;
    } else {
      num = -num;
      neg = '-';
    }
  }
  num = '' + num;
  while (num.length < digits) num = ZERO_CHAR + num;
  if (trim) {
    num = num.substr(num.length - digits);
  }
  return neg + num;
}
@ngdoc directive
@name ngBindTemplate

@description
The `ngBindTemplate` directive specifies that the element
text content should be replaced with the interpolation of the template
in the `ngBindTemplate` attribute.
Unlike `ngBind`, the `ngBindTemplate` can contain multiple `{{` `}}`
expressions. This directive is needed since some HTML elements
(such as TITLE and OPTION) cannot contain SPAN elements.

@element ANY
@param {string} ngBindTemplate template of form
  <tt>{{</tt> <tt>expression</tt> <tt>}}</tt> to eval.

@example
Try it here: enter text in text box and watch the greeting change.
   <example module="bindExample" name="ng-bind-template">
     <file name="index.html">
       <script>
         angular.module('bindExample', [])
           .controller('ExampleController', ['$scope', function($scope) {
             $scope.salutation = 'Hello';
             $scope.name = 'World';
           }]);
       </script>
       <div ng-controller="ExampleController">
        <label>Salutation: <input type="text" ng-model="salutation"></label><br>
        <label>Name: <input type="text" ng-model="name"></label><br>
        <pre ng-bind-template="{{salutation}} {{name}}!"></pre>
       </div>
     </file>
     <file name="protractor.js" type="protractor">
       it('should check ng-bind', function() {
         var salutationElem = element(by.binding('salutation'));
         var salutationInput = element(by.model('salutation'));
         var nameInput = element(by.model('name'));

         expect(salutationElem.getText()).toBe('Hello World!');

         salutationInput.clear();
         salutationInput.sendKeys('Greetings');
         nameInput.clear();
         nameInput.sendKeys('user');

         expect(salutationElem.getText()).toBe('Greetings user!');
       });
     </file>
   </example>