text: from __future__ import annotations
  
  import argparse
  from typing import Any
  from typing import Generator
  from typing import NamedTuple
  from typing import Sequence
  
  import ruamel.yaml
  
  yaml = ruamel.yaml.YAML(typ='safe')
  
  
  def _exhaust(gen: Generator[str, None, None]) -> None:
      for _ in gen:
          pass
  
  
  def _parse_unsafe(*args: Any, **kwargs: Any) -> None:
      _exhaust(yaml.parse(*args, **kwargs))
  
  
  def _load_all(*args: Any, **kwargs: Any) -> None:
      _exhaust(yaml.load_all(*args, **kwargs))
  
  
  class Key(NamedTuple):
      multi: bool
      unsafe: bool
  
  
  LOAD_FNS = {
      Key(multi=False, unsafe=False): yaml.load,
      Key(multi=False, unsafe=True): _parse_unsafe,
      Key(multi=True, unsafe=False): _load_all,
      Key(multi=True, unsafe=True): _parse_unsafe,
  }
  
  
  def main(argv: Sequence[str] | None = None) -> int:
      parser = argparse.ArgumentParser()
      parser.add_argument(
          '-m', '--multi', '--allow-multiple-documents', action='store_true',
      )
      parser.add_argument(
          '--unsafe', action='store_true',
          help=(
              'Instead of loading the files, simply parse them for syntax.  '
              'A syntax-only check enables extensions and unsafe contstructs '
              'which would otherwise be forbidden.  Using this option removes '
              'all guarantees of portability to other yaml implementations.  '
              'Implies --allow-multiple-documents'
          ),
      )
      parser.add_argument('filenames', nargs='*', help='Filenames to check.')
      args = parser.parse_args(argv)
  
      load_fn = LOAD_FNS[Key(multi=args.multi, unsafe=args.unsafe)]
  
      retval = 0
      for filename in args.filenames:
          try:
              with open(filename, encoding='UTF-8') as f:
                  load_fn(f)
          except ruamel.yaml.YAMLError as exc:
              print(exc)
              retval = 1
      return retval
  
  
  if __name__ == '__main__':
      raise SystemExit(main())