function sortedKeys(obj) {
  var keys = [];
  for (var key in obj) {
    if (obj.hasOwnProperty(key)) {
      keys.push(key);
    }
  }
  return keys.sort();
}
@ngdoc function
@name angular.forEach
@module ng
@function

@description
Invokes the `iterator` function once for each item in `obj` collection, which can be either an
object or an array. The `iterator` function is invoked with `iterator(value, key)`, where `value`
is the value of an object property or an array element and `key` is the object property key or
array element index. Specifying a `context` for the function is optional.

It is worth noting that `.forEach` does not iterate over inherited properties because it filters
using the `hasOwnProperty` method.

   ```js
     var values = {name: 'misko', gender: 'male'};
     var log = [];
     angular.forEach(values, function(value, key){
       this.push(key + ': ' + value);
     }, log);
     expect(log).toEqual(['name: misko', 'gender: male']);
   ```

@param {Object|Array} obj Object to iterate over.
@param {Function} iterator Iterator function.
@param {Object=} context Object to become context (`this`) for the iterator function.
@returns {Object|Array} Reference to `obj`.