code: def parse_library(lib_files):
      
      tracks, playlists = lib_files
      lib = MusicLibrary()
      lib_length = len(tracks)
      i = 0
  
      writer = lib.ix.writer()
      previous_procent_done_str = ""
      for f in tracks:
          track_info = TrackInfo(f)
          lib.add_track_internal(track_info, writer)
          current_percent_done_str = "%d%%" % (i / lib_length * 100)
          if current_percent_done_str != previous_procent_done_str:
              logs.print_info("Analizowanie biblioteki muzycznej... " + current_percent_done_str)
              previous_procent_done_str = current_percent_done_str
          i += 1.0
      logs.print_info("Analizowanie playlist...")
      for f in playlists:
          with open(f, 'r') as fo:
              playlist_dict = loads(fo.read())
              playlist = Playlist(lib, f, playlist_dict['title'], playlist_dict['tracks'])
              lib.add_playlist(playlist)
      writer.commit()
      logs.print_info("Optymalizacja index-u...")
      lib.ix.optimize()
      return lib
docs: Analizuje pliki podane w liście lib_files
      Zwraca instancję MusicLibrary