code: def train_sar(params, data):
      model = SAR(**params)
      model.set_index(data)
      with Timer() as t:
          model.fit(data)
      return model, t
  
imports: import os
  import numpy
  import pandas
  from tempfile import TemporaryDirectory
  import surprise
  import cornac
  from recommenders.utils.timer import Timer
  from recommenders.utils.constants import COL_DICT, DEFAULT_K, DEFAULT_USER_COL, DEFAULT_ITEM_COL, DEFAULT_RATING_COL, DEFAULT_PREDICTION_COL, DEFAULT_TIMESTAMP_COL, SEED
  from recommenders.models.sar import SAR
  from recommenders.models.surprise.surprise_utils import predict, compute_ranking_predictions
  from recommenders.models.cornac.cornac_utils import predict_ranking
  from recommenders.evaluation.python_evaluation import map, ndcg_at_k, precision_at_k, recall_at_k
  from recommenders.evaluation.python_evaluation import rmse, mae, rsquared, exp_var
label_desc: Use image node_id 23 for calling a global function with example usage: train_sar(params, data) and returns: model,  t