code: def walk(
      top: PathType,
      topdown: bool = True,
      onerror: Optional[Callable[..., None]] = None,
  ) -> Iterable[Tuple[PathType, List[PathType], List[PathType]]]:
      """Return an iterator walking a directory tree."""
      return _get_filesystem(top).walk(
          top, topdown=topdown, onerror=onerror
      )
  
imports: from typing import Any, Callable, Iterable, List, Optional, Tuple, Type
  from tfx.dsl.io import filesystem
  from tfx.dsl.io import filesystem_registry
  from tfx.dsl.io.filesystem import PathType
  import tfx.dsl.io.plugins.tensorflow_gfile
  import tfx.dsl.io.plugins.local
label_desc: Use image node_id 14 for calling a global function with example usage: walk(top, topdown, onerror) and returns: _get_filesystem