code: def validate(package, test_target_type=None):
      
      project = Project(package)
  
      if test_target_type is None:
          test_target_type = detect_target_type()
  
      if test_target_type == BalletTestTypes.PROJECT_STRUCTURE_VALIDATION:
          check_project_structure(project)
      elif test_target_type == BalletTestTypes.FEATURE_API_VALIDATION:
          validate_feature_api(project)
      elif test_target_type == BalletTestTypes.FEATURE_ACCEPTANCE_EVALUTION:
          evaluate_feature_performance(project)
      elif test_target_type == (
              BalletTestTypes.FEATURE_PRUNING_EVALUATION):
          prune_existing_features(project)
      else:
          raise NotImplementedError(
              'Unsupported test target type: {test_target_type}'
              .format(test_target_type=test_target_type))
docs: Entrypoint for ./validate.py script in ballet projects