Is your feature request related to a problem? Please describe.
When the content request comes in and the processing will be delayed, duplicating the memory creates memory pressure. I would like to be able to swap the content string into my own string so I don't have to make a copy, but I plan to return the response to the sender before completion (which in my case is a re-direct)

Describe why the feature or enhancement you are proposing fits the library.
The content is not necessary to be used by the library once I have received it

Describe the solution you'd like
Either I'd like to be able to get a non-constant pointer to the content, or a way to pass my std::string for the swap within the lirbary

Describe alternatives you've considered
I make a copy now. I've considered just modifying the code I have myself and still might. I could easily submit a PR for this but have not contributed to this project before

Additional context
Add any other context or screenshots about the feature request here.