text: import _pickle as cP
  
  fw = open("index_MSD.tsv","w") # where to save the file?
  
  train_list = cP.load(open('filtered_list_train.cP','rb'))
  test_list = cP.load(open('filtered_list_test.cP','rb'))
  id7d_to_path = cP.load(open('7D_id_to_path.pkl','rb'))
  idmsd_to_id7d = cP.load(open('MSD_id_to_7D_id.pkl','rb'))
  idmsd_to_tag = cP.load(open('msd_id_to_tag_vector.cP','rb'))
  
  for idmsd in train_list:
      path = idmsd[2]+'/'+idmsd[3]+'/'+idmsd[4]+'/'+idmsd+'.mp3'
      fw.write("%s\t%s\n" % (idmsd,path))
  
  for idmsd in test_list:
      path = idmsd[2]+'/'+idmsd[3]+'/'+idmsd[4]+'/'+idmsd+'.mp3'
      fw.write("%s\t%s\n" % (idmsd,path))
   
  # for loading a file (train_list[0])
  # file_dir = id7d_to_path[idmsd_to_id7d[train_list[0]]]
  
  # for loading 50 tag vector of (train_list[0])
  # tag_boolean = idmsd_to_tag[train_list[0]]
  print('Done!')
  