code: def help_string():
    
    help_str = """
  Registry contents:
  ------------------
  
    Models:
  %s
  
    HParams:
  %s
  
    RangedHParams:
  %s
  
    Problems:
  %s
  
    Optimizers:
  %s
  
    Attacks:
  %s
  
    Attack HParams:
  %s
  
    Pruning HParams:
  %s
  
    Pruning Strategies:
  %s
  
    Env Problems:
  %s
  """
    lists = tuple(
        display_list_by_prefix(entries, starting_spaces=4) for entries in [  # pylint: disable=g-complex-comprehension
            list_models(),
            list_hparams(),
            list_ranged_hparams(),
            list_base_problems(),
            list_optimizers(),
            list_attacks(),
            list_attack_params(),
            list_pruning_params(),
            list_pruning_strategies(),
            list_env_problems(),
        ])
    return help_str % lists
docs: Generate help string with contents of registry.