class_docstr: Api for metadata storage.
docstr: To be called at the beginning of model_fn for training a new trial.
code: def before_generating_trial_model(self, trial_id, model_dir):
      """To be called at the beginning of model_fn for training a new trial."""
  
file_path: model_search/model_search/metadata/metadata.py
imports: import abc
label_desc: Use image node_id 2 for calling the MetaData obj's underlying member method code with example usage: obj.before_generating_trial_model(trial_id, model_dir) without return types