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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def set_resolved_url(self, item=None, subtitles=None):
        '''Takes a url or a listitem to be played. Used in conjunction with a
        playable list item with a path that calls back into your addon.

        :param item: A playable list item or url. Pass None to alert XBMC of a
                     failure to resolve the item.

                     .. warning:: When using set_resolved_url you should ensure
                                  the initial playable item (which calls back
                                  into your addon) doesn't have a trailing
                                  slash in the URL. Otherwise it won't work
                                  reliably with XBMC's PlayMedia().
        :param subtitles: A URL to a remote subtitles file or a local filename
                          for a subtitles file to be played along with the
                          item.
        '''
        if self._end_of_directory:
            raise Exception('Current XBMC handle has been removed. Either '
                            'set_resolved_url(), end_of_directory(), or '
                            'finish() has already been called.')
        self._end_of_directory = True

        succeeded = True
        if item is None:
            # None item indicates the resolve url failed.
            item = {}
            succeeded = False

        if isinstance(item, basestring):
            # caller is passing a url instead of an item dict
            item = {'path': item}

        item = self._listitemify(item)
        item.set_played(True)
        xbmcplugin.setResolvedUrl(self.handle, succeeded,
                                  item.as_xbmc_listitem())

        # call to _add_subtitles must be after setResolvedUrl
        if subtitles:
            self._add_subtitles(subtitles)
        return [item]