201               suffix=None,  argument
209     if suffix and not isinstance(suffix, str):
213         if suffix and not filename.endswith(suffix):
219               suffix=None,  argument
227     suffix = suffix or ''
228     if not isinstance(suffix, str):
237 def iter_files(root, suffix=None, relparent=None, *,  argument
256             yield from iter_files(root, suffix, relparent,
269     if suffix and not isinstance(suffix, str):
271         suffix = tuple(suffix)
273         filenames = get_files(root, suffix=suffix)
274         suffix = None
277         if suffix and not isinstance(suffix, str):  # multiple suffixes
278             if not filename.endswith(suffix):
296     for suffix in suffixes:
297         yield from _iter_files(root, suffix, relparent)