class_docstr: The Tuning objective for HPO.
docstr: Get the target metric.
docstr_tok: ["Get","the","target","metric","."]
code: def target_metric(self):
      """Get the target metric."""
      return self.target_metric_
  
file_path: BigDL/python/nano/src/bigdl/nano/automl/tf/objective.py
imports: from selectors import EpollSelector
  from tensorflow.keras.backend import clear_session
  from tensorflow.keras.models import clone_model
  import tensorflow
  import inspect
  import copy
  from bigdl.nano.automl.hpo.backend import create_tfkeras_pruning_callback
  from bigdl.nano.utils.common import invalidInputError
label_desc: Use image node_id 2 for calling the Objective obj's underlying member method code with example usage: obj.target_metric() and returns: self