code: def get_juman_command() -> Optional[Literal["juman", "jumanpp"]]:
      for cmd in ["jumanpp", "juman"]:
          if distutils.spawn.find_executable(cmd):
              return cmd  # type: ignore
      return None
  
imports: from dataclasses import dataclass
  from camphr.doc import Doc, UserDataProto
  import itertools
  import distutils.spawn
  from typing import Any, Callable, Dict, Iterator, List, Optional
  from typing_extensions import Literal
  from camphr.serde import SerializationMixin
label_desc: Use image node_id 1 for calling a global function with example usage: get_juman_command() and returns: None, cmd