Example of executing code after first post to a thread?

[Kevin]

Any examples of executing some code after the first, and only the first, post of a thread? Essentially I just want to have some code kick in after somebody replies to an existing thread for the first time and if that post response is not flagged for spam, etc..

If there are any examples I could check out, that'd be really appreciated, thanks.
Example of executing code after first post to a thread?

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