<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def item_extra_kwargs(self, action):
 """ Returns an extra keyword arguments dictionary that is used with the `add_item` call of the feed generator. Add the 'content' field of the 'Entry' item, to be used by the custom feed generator. """

        item = self.format(action)
        item.pop('title', None)
        item['uri'] = item.pop('url')
        item['activity:verb'] = item.pop('verb')
        return item