def time_delta(t_delta: float) -> str:
    """
    Convert a timestamp into a human readable timestring.
    Args:
        t_delta (float): Difference between two timestamps of time.time()

    Returns:
        Human readable timestring.
    """
    hours = round(t_delta // 3600)
    minutes = round(t_delta // 60 % 60)
    seconds = round(t_delta % 60)
    millisecs = round(t_delta % 1 * 1000)
    return f"{hours} hours, {minutes} minutes, {seconds} seconds, {millisecs} milliseconds"