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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 get_now_playing(self):
 """ Returns the currently playing track, or None if nothing is playing. """


        params = self._get_params()
        params["limit"] = "1"

        doc = self._request(self.ws_prefix + ".getRecentTracks", False, params)

        tracks = doc.getElementsByTagName("track")

        if len(tracks) == 0:
            return None

        e = tracks[0]

        if not e.hasAttribute("nowplaying"):
            return None

        artist = _extract(e, "artist")
        title = _extract(e, "name")

        return Track(artist, title, self.network, self.name)