Rating:
Flag 1:
Notice that their program beta reduces terms even within abstractions.
Try:
```ml
bot_t = (p : #0) => p
not_not = (p: #0) -> (_ : (_ : p) => bot_t) => bot_t
easy_t = (phi : #0) => (_ : (not_not phi)) => phi
(easy:easy_t) -> (_:#0) -> (flag1 easy)
```
