[Compiler.extractClosed] size: 3
    def foo._closed_0 : SourceInfo :=
      let _x.1 := false;
      let _x.2 := Syntax.missing;
      let _x.3 := @SourceInfo.fromRef _x.2 _x.1;
      return _x.3
[Compiler.extractClosed] size: 1
    def foo._closed_1 : String :=
      let _x.1 := "UnhygienicMain";
      return _x.1
[Compiler.extractClosed] size: 2
    def foo._closed_2 : Name :=
      let _x.1 := foo._closed_1;
      let _x.2 := Name.mkStr1 _x.1;
      return _x.2
[Compiler.extractClosed] size: 1
    def foo._closed_3 : String :=
      let _x.1 := "term_+_";
      return _x.1
[Compiler.extractClosed] size: 2
    def foo._closed_4 : Name :=
      let _x.1 := foo._closed_3;
      let _x.2 := Name.mkStr1 _x.1;
      return _x.2
[Compiler.extractClosed] size: 1
    def foo._closed_5 : String :=
      let _x.1 := "a";
      return _x.1
[Compiler.extractClosed] size: 2
    def foo._closed_6 : Substring.Raw :=
      let _x.1 := foo._closed_5;
      let _x.2 := String.toRawSubstring' _x.1;
      return _x.2
[Compiler.extractClosed] size: 2
    def foo._closed_7 : Name :=
      let _x.1 := foo._closed_5;
      let _x.2 := Name.mkStr1 _x.1;
      return _x.2
[Compiler.extractClosed] size: 4
    def foo._closed_8 : Name :=
      let _x.1 := 1;
      let _x.2 := foo._closed_7;
      let _x.3 := foo._closed_2;
      let _x.4 := addMacroScope _x.3 _x.2 _x.1;
      return _x.4
[Compiler.extractClosed] size: 5
    def foo._closed_9 : Syntax :=
      let _x.1 := [] ◾;
      let _x.2 := foo._closed_8;
      let _x.3 := foo._closed_6;
      let _x.4 := foo._closed_0;
      let _x.5 := Syntax.ident _x.4 _x.3 _x.2 _x.1;
      return _x.5
[Compiler.extractClosed] size: 1
    def foo._closed_10 : String :=
      let _x.1 := "+";
      return _x.1
[Compiler.extractClosed] size: 3
    def foo._closed_11 : Syntax :=
      let _x.1 := foo._closed_10;
      let _x.2 := foo._closed_0;
      let _x.3 := Syntax.atom _x.2 _x.1;
      return _x.3
[Compiler.extractClosed] size: 8
    def foo n : Syntax :=
      let _x.1 := foo._closed_0;
      let _x.2 := foo._closed_4;
      let _x.3 := foo._closed_9;
      let _x.4 := foo._closed_11;
      let _x.5 := Nat.reprFast n;
      let _x.6 := SourceInfo.none;
      let _x.7 := @Syntax.mkNumLit _x.5 _x.6;
      let _x.8 := Syntax.node3 _x.1 _x.2 _x.3 _x.4 _x.7;
      return _x.8