def find_files_by_suffix_recursively(root: str, suffix: Union[str, List[str]]):
    """
    Args:
        root: path to the directory to start search files
        suffix: any str as suffix, or can match multiple such strings
            when input is List[str]. 
            Example 1, e.g., suffix: `.jpg` or [`.jpg`, `.png`]
            Example 2, e.g., use a `*` in the `suffix`: `START*.jpg.`.
    """
    if isinstance(suffix, str):
        suffix = [suffix, ]
    filepaths = flat_list_of_lists(
        [list(Path(root).rglob(f"*{e}")) for e in suffix])
    return filepaths

    Args:
        root: path to the directory to start search files
        suffix: any str as suffix, or can match multiple such strings
            when input is List[str]. 
            Example 1, e.g., suffix: `.jpg` or [`.jpg`, `.png`]
            Example 2, e.g., use a `*` in the `suffix`: `START*.jpg.`.
    
video_chat/utils/basic_utils.py