Directive block - Gen<None> - 26 - (0:0,0)
    Code span - Gen<Stmt> - [LF  ] - SpanEditHandler;Accepts:Any - (0:0,0) - Tokens:2
        SyntaxKind.NewLine;[LF];
        SyntaxKind.Whitespace;[  ];
    Transition span - Gen<None> - [@] - SpanEditHandler;Accepts:None - (4:1,2) - Tokens:1
        SyntaxKind.Transition;[@];
    MetaCode span - Gen<None> - [addTagHelper] - SpanEditHandler;Accepts:None - (5:1,3) - Tokens:1
        SyntaxKind.Identifier;[addTagHelper];
    Markup span - Gen<None> - [ ] - SpanEditHandler;Accepts:None - (17:1,15) - Tokens:1
        SyntaxKind.Whitespace;[ ];
    Code span - Gen<AddTagHelper:{"*, Foo";*, Foo;*;Foo}> - ["*, Foo"] - SpanEditHandler;Accepts:AnyExceptNewline - (18:1,16) - Tokens:1
        SyntaxKind.StringLiteral;["*, Foo"];
