➜ half_half_tco ruby half_half.rb
<compiled>:4:in `centaur': stack level too deep (SystemStackError)
from <compiled>:6:in `centaur'
from <compiled>:6:in `centaur'
from <compiled>:6:in `centaur'
from <compiled>:6:in `centaur'
from <compiled>:6:in `centaur'
from <compiled>:6:in `centaur'
from <compiled>:6:in `centaur'
from <compiled>:6:in `centaur'
... 8177 levels...
from <compiled>:6:in `centaur'
from <compiled>:6:in `centaur'
from <compiled>:6:in `centaur'
from half_half.rb:25:in `<main>'
➜ half_half_tco ruby half_half.rb -TCO
To infinity and beyond!
note it all started from here: