def string_to_list(list_string, delimiter=","):
    """Convert object as string into a list of objects.

    If the object is already a list, return the list.

    Args:
        list_string (str):
            List as string, e.g., "[a, b, c]"
        delimiter (str):
            Character(s) separating strings.

    Returns:
        List of objects, e.g., ["a", "b", "c"]
    """
    if isinstance(list_string, list):
        return list_string

    PATTERN = "[\[\(]?([\w\s,]+)[\]\)]?"
    values = [value.strip() for value in list_string[1:-1].split(delimiter)]
    return values