WeChat development reply Success What does it mean?

This is said in the development documentation

But what does that mean? How do I reply to success? How do I reply to an empty string?

Searched all over the net, all just excerpt this passage, did not say how to operate.
Trouble Big God write a piece of code, I really do not know what the meaning of this. Thank you.

Reply content:

This is said in the development documentation

But what does that mean? How do I reply to success? How do I reply to an empty string?

Searched all over the net, all just excerpt this passage, did not say how to operate.
Trouble Big God write a piece of code, I really do not know what the meaning of this. Thank you.

If your return code should be an XML containing the contents of your reply when you push normally
When you do not want to reply to the message live can not in 5 seconds response time should be directly reply to a success or empty string.
Note that the success here means only the output of this thing is equivalent to echo ' success '; not a reply is success XML

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