whileTestPSemSound : (c : ℕ ) (output : Envc ) → 
  output ≡ whileTestP c (λ e → e) 
  → ⊤ implies ((vari output ≡ 0) ∧ (varn output ≡ c))
whileTestPSemSound c output refl = whileTestPSem c