Returns the dead letter queue name for a given queue.  If the
    given queue name belongs to a delayed queue, the dead letter queue
    name for the original queue is generated.

def xq_name(queue_name):
    """Returns the dead letter queue name for a given queue.  If the
    given queue name belongs to a delayed queue, the dead letter queue
    name for the original queue is generated.
    """
    if queue_name.endswith(".XQ"):
        return queue_name

    if queue_name.endswith(".DQ"):
        queue_name = queue_name[:-3]
    return queue_name + ".XQ"