code: def _create_default_estimator(self, loss_key=None, hparams=None):
      return tfr_estimator.EstimatorBuilder(
          _context_feature_columns(),
          _example_feature_columns(),
          _scoring_function,
          hparams=(hparams or _get_hparams(loss_key)),
      )
  
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 the EstimatorBuilderTest obj's underlying member method code with example usage: obj._create_default_estimator(loss_key, hparams) and returns: tfr_estimator