from pathlib import Path


def check_arg_input_dir(input_dir: str) -> bool:
    """Return True of the input_dir exists.

    :param input_dir: the output directory
    :return: True if the directory exists.
    """
    # output_format
    p = Path(input_dir)
    if not p.is_dir():
        raise ValueError(f"Error! Input dir could not be found at '{input_dir}'.")

    return True