code: def ensure_list(item: Union[Iterable[str], str, None]) -> List[str]:
      if item is None:
          return []
      if isinstance(item, str):
          return [item]
      return list(item)
  
file_path: dvc/dvc/utils/collections.py
imports: from collections.abc import Mapping
  from typing import Dict, Iterable, List, Union, no_type_check
label_desc: Use image node_id 6 for calling a global function with example usage: ensure_list(item) and returns: list, list, list