def get_function_args(test):
    """
    Use repr() on arguments used for the students defined function.
    If no arguments is used, return None.
    """
    try:
        return repr(getattr(test, "_argument"))
    except AttributeError:
        try:
            return ", ".join([repr(arg) for arg in getattr(test, "_multi_arguments")])
        except AttributeError:
            return None