code: def context_feature_columns():
      """Returns context feature columns."""
      return {}
  
file_path: ranking/tensorflow_ranking/research/dasalc.py
imports: from absl import flags
  import tensorflow
  from tensorflow import estimator
  from tensorflow.python.estimator.canned import optimizers
  import tensorflow_ranking
label_desc: Use image node_id 1 for calling a global function with example usage: context_feature_columns() and returns: dict