code: def model_fn(model_dir):
      """Deserialize and return fitted model.
  
      Note that this should have the same name as the serialized model in the _xgb_train method
      """
      booster = xgb.Booster()
      booster.load_model(os.path.join(model_dir, model_filename))
      return booster
  
imports: import argparse
  import os
  from sagemaker_xgboost_container.data_utils import get_dmatrix
  import xgboost
label_desc: Use image node_id 1 for calling a global function with example usage: model_fn(model_dir) and returns: booster