let a : num := 10, b : num := 10, c : num := 10 in f a b (f a 10 c) : num
let a : num := 10,
    b : num := let c : num := 10 in f a c (f a a (f 10 a c)),
    d : num := 10,
    e : num := f (f 10 10 d) (f d 10 10) a
in f a b (f e d 10) :
  num
