You can run app.rb to launch a stand-in for the Valued API. It will output any event payloads received to the console, with some highlighting.
Install ruby via asdf.
If you don't already have the asdf ruby plugin installed run asdf plugin add ruby https://github.com/asdf-vm/asdf-ruby.git
Run asdf install to install ruby
Run bundle install to install gems
To start the server run ruby app.rb