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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_song_lyric(self, song_id):
 """Get a song's lyric. warning: use old api. :params song_id: song id. :return: a song's lyric. """


        url = 'http://music.163.com/api/song/lyric?os=osx&id={}&lv=-1&kv=-1&tv=-1'.format(  # NOQA
            song_id)
        result = self.get_request(url)
        if 'lrc' in result and result['lrc']['lyric'] is not None:
            lyric_info = result['lrc']['lyric']
        else:
            lyric_info = 'Lyric not found.'
        return lyric_info