Where and How can i see the Stream that contains the response back to the client of a CSP application

Hey, So the title pretty much describes the question:
Where and How can i see the Stream that contains the response back to the client of a CSP application.

When the request is being processed and finished we return a response to the client - We do that by writing the data to a stream and that stream is sent back to the client.
I wanted to know how i can access the point right before that Data is actually written to the client back (meaning the place where the response is actually being send back, the last point of contact).
And was not able to find about it in the DOCS so would love to get a reference to it if you know where.