code: def context_feature_column():
      return {}
  
imports: import os
  from absl.testing import parameterized
  import six
  import tensorflow
  from tensorflow import estimator
  from google.protobuf import text_format
  from tensorflow_ranking.python import data
  from tensorflow_ranking.python import estimator
  from tensorflow_ranking.python import feature
  from tensorflow_serving.apis import input_pb2
label_desc: Use image node_id 1 for calling a global function with example usage: context_feature_column() and returns: dict