((S
  (Stmt (Assign (Var . "id") (Term (Abs (Var . "x") (Term (Var . "x"))))))
  (S
   (Stmt
    (Term
     (Abs
      (Var . "s")
      (Term
       (Abs
        (Var . "z")
        (Term
         (Term
          (App
           (Term (App (Term (Var . "s")) (Term (Var . "s"))))
           (Term (Var . "z"))))))))))
   (S
    (Stmt
     (Assign
      (Var . "tru")
      (Term
       (Abs (Var . "t") (Term (Abs (Var . "f") (Term (Var . "t"))))))))))))