[init]
def sefFn (x_1 : obj) (x_2 : obj) : obj :=
  case x_1 : obj of
  Lean.Expr.bvar →
    ret x_1
  Lean.Expr.fvar →
    ret x_1
  Lean.Expr.mvar →
    ret x_1
  Lean.Expr.sort →
    ret x_1
  Lean.Expr.const →
    ret x_1
  Lean.Expr.app →
    let x_3 : obj := proj[1] x_1;
    let x_4 : obj := Lean.Expr.updateApp x_1 x_2 x_3 ◾;
    ret x_4
  Lean.Expr.lam →
    ret x_1
  Lean.Expr.forallE →
    ret x_1
  Lean.Expr.letE →
    ret x_1
  Lean.Expr.lit →
    ret x_1
  Lean.Expr.mdata →
    ret x_1
  Lean.Expr.proj →
    ret x_1