dannykopping/Slim — comment on commit 3fdc30d98d5038ec9520420fa6d81ef9de24b8a7
File:  line 0
By codeguy:

What if we assigned the callable's return value to the Response body? This avoids the long-term need for output buffering (not that ob is a problem), and may also solve what you are trying to do. Just tossing around some ideas to hash this out.