[init]
def sefFn (x_1 : obj) (x_2 : obj) : obj :=
  case x_1 : obj of
  Lean.Expr.bvar._impl →
    ret x_1
  Lean.Expr.fvar._impl →
    ret x_1
  Lean.Expr.mvar._impl →
    ret x_1
  Lean.Expr.sort._impl →
    ret x_1
  Lean.Expr.const._impl →
    ret x_1
  Lean.Expr.app._impl →
    let x_3 : obj := proj[0] x_1;
    let x_4 : obj := proj[1] x_1;
    let x_5 : usize := ptrAddrUnsafe ◾ x_3;
    let x_6 : usize := ptrAddrUnsafe ◾ x_2;
    let x_7 : u8 := USize.decEq x_5 x_6;
    case x_7 : obj of
    Bool.false →
      let x_8 : obj := Lean.Expr.app._override x_2 x_4;
      ret x_8
    Bool.true →
      let x_9 : usize := ptrAddrUnsafe ◾ x_4;
      let x_10 : u8 := USize.decEq x_9 x_9;
      case x_10 : obj of
      Bool.false →
        let x_11 : obj := Lean.Expr.app._override x_2 x_4;
        ret x_11
      Bool.true →
        ret x_1
  Lean.Expr.lam._impl →
    ret x_1
  Lean.Expr.forallE._impl →
    ret x_1
  Lean.Expr.letE._impl →
    ret x_1
  Lean.Expr.lit._impl →
    ret x_1
  Lean.Expr.mdata._impl →
    ret x_1
  Lean.Expr.proj._impl →
    ret x_1