code: def _available_plugin_modules() -> Sequence[str]:
      # tiktoken_ext is a namespace package
      # submodules inside tiktoken_ext will be inspected for ENCODING_CONSTRUCTORS attributes
      # - we use namespace package pattern so `pkgutil.iter_modules` is fast
      # - it's a separate top-level package because namespace subpackages of non-namespace
      #   packages don't quite do what you want with editable installs
      mods = []
      plugin_mods = pkgutil.iter_modules(
          tiktoken_ext.__path__, tiktoken_ext.__name__ + "."
      )
      for _, mod_name, _ in plugin_mods:
          mods.append(mod_name)
      return mods
  
file_path: tiktoken/tiktoken/registry.py
imports: from __future__ import annotations
  import functools
  import importlib
  import pkgutil
  import threading
  from typing import Any, Callable, Optional, Sequence
  import tiktoken_ext
  from tiktoken.core import Encoding
label_desc: Use image node_id 1 for calling a global function with example usage: _available_plugin_modules() and returns: mods