<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def message_info(exchange, routing_key, properties):
 """Return info about a message using the same conditional constructs :param str exchange: The exchange the message was published to :param str routing_key: The routing key used :param properties: The AMQP message properties :type properties: pika.spec.Basic.Properties :rtype: str """

    output = []
    if properties.message_id:
        output.append(properties.message_id)
    if properties.correlation_id:
        output.append('[correlation_id="{}"]'.format(
            properties.correlation_id))
    if exchange:
        output.append('published to "{}"'.format(exchange))
    if routing_key:
        output.append('using "{}"'.format(routing_key))
    return ' '.join(output)