Helper function that formats most recent traceback.  Useful when a program has an overall try/except
    and it wants to output the program trace to the log.
    :return: formatted traceback string (or None if no traceback available)

def traceback_string():
    """
    Helper function that formats most recent traceback.  Useful when a program has an overall try/except
    and it wants to output the program trace to the log.
    :return: formatted traceback string (or None if no traceback available)
    """
    tb_string = None
    exc_type, exc_value, exc_traceback = traceback.sys.exc_info()
    if exc_type is not None:
        display_lines_list = [str(exc_value)] + traceback.format_tb(exc_traceback)
        tb_string = "\n".join(display_lines_list)
    return tb_string