Returns the list of changed values.
        The key is added to each item.

        selection
            Specifies the desired changes.
            Supported values are
                ``all`` - all changed items are included in the output
                ``intersect`` - changed items present in both lists are included

def changed(self, selection='all'):
        '''
        Returns the list of changed values.
        The key is added to each item.

        selection
            Specifies the desired changes.
            Supported values are
                ``all`` - all changed items are included in the output
                ``intersect`` - changed items present in both lists are included
        '''
        changed = []
        if selection == 'all':
            for recursive_item in self._get_recursive_difference(type='all'):
                # We want the unset values as well
                recursive_item.ignore_unset_values = False
                key_val = six.text_type(recursive_item.past_dict[self._key]) \
                        if self._key in recursive_item.past_dict \
                        else six.text_type(recursive_item.current_dict[self._key])

                for change in recursive_item.changed():
                    if change != self._key:
                        changed.append('.'.join([self._key, key_val, change]))
            return changed
        elif selection == 'intersect':
                # We want the unset values as well
            for recursive_item in self._get_recursive_difference(type='intersect'):
                recursive_item.ignore_unset_values = False
                key_val = six.text_type(recursive_item.past_dict[self._key]) \
                        if self._key in recursive_item.past_dict \
                        else six.text_type(recursive_item.current_dict[self._key])

                for change in recursive_item.changed():
                    if change != self._key:
                        changed.append('.'.join([self._key, key_val, change]))
            return changed