I can only recommend webmachine here, <a href="https:&#x2F;&#x2F;raw.githubusercontent.com&#x2F;webmachine&#x2F;webmachine.github.io&#x2F;master&#x2F;images&#x2F;http-headers-status-v3.png" rel="nofollow">https:&#x2F;&#x2F;raw.githubusercontent.com&#x2F;webmachine&#x2F;webmachine.gith...</a>. (it starts at b14)<p>This is actual code drawn out as a state diagram.
It&#x27;s officially available for Erlang and Ruby.
(Disclaimer: I am one of the &quot;maintainers&quot; of the Ruby version)