-- non-dependent coe should reduce to its body

def five  : ℕ = 5
def five? : ℕ = coe ℕ 5

def eq : five ≡ five? : ℕ = δ _ ⇒ 5

def subst1 : 0.(P : ℕ → ★) → P five  → P five? = λ P p ⇒ p
def subst2 : 0.(P : ℕ → ★) → P five? → P five  = λ P p ⇒ p