PHP：这个库如何拦截curl函数？

I'm using a library called PHP-VCR for mocking HTTP requests in my tests. I see that this library intercepts curl methods (e.g. curl_init, curl_setopts, etc.), and I'm using it successfully, but I'm not following the actual intercepting or monkey-patching mechanism of it.

In the following stack trace, it goes from curl_init being called in Stripe\..\CurlClient to VCR\...\CurlHook::curl_init. How is this jump made?