code: def register_mutator(name: str) -> Callable[[Type], Type]:
      """
      Register a mutator.
      """
  
      def _inner(cls_: Type) -> Type:
          global MUTATOR_REGISTRY
          if (
              name in MUTATOR_REGISTRY
              and cls_ is not MUTATOR_REGISTRY[name]
          ):
              raise NameError(
                  "Mutators must be uniquely named, but detected two mutators with "
                  f"the name '{name}'."
              )
          MUTATOR_REGISTRY[name] = cls_
          return cls_
  
      return _inner
  
imports: from __future__ import annotations
  import abc
  import importlib
  import pkgutil
  from typing import Optional, Iterable, Tuple, List, Iterator, Callable, Type
  import parlai.mutators
  from parlai.core.params import ParlaiParser
  from parlai.core.opt import Opt
  from parlai.core.message import Message
label_desc: Use image node_id 2 for calling a global function with example usage: register_mutator(name) and returns: _inner, cls_