Directive block - Gen<None> - 32 - (0:0,0)
    Transition span - Gen<None> - [@] - SpanEditHandler;Accepts:None - (0:0,0) - Symbols:1
        CSharpSymbolType.Transition;[@];
    MetaCode span - Gen<None> - [addTagHelper] - SpanEditHandler;Accepts:None - (1:0,1) - Symbols:1
        CSharpSymbolType.Identifier;[addTagHelper];
    Markup span - Gen<None> - [     ] - SpanEditHandler;Accepts:None - (13:0,13) - Symbols:1
        CSharpSymbolType.WhiteSpace;[     ];
    Code span - Gen<AddTagHelper:{Foo,   Bar;Foo,   Bar;Foo;Bar}> - [Foo,   Bar    ] - SpanEditHandler;Accepts:AnyExceptNewline - (18:0,18) - Symbols:5
        CSharpSymbolType.Identifier;[Foo];
        CSharpSymbolType.Comma;[,];
        CSharpSymbolType.WhiteSpace;[   ];
        CSharpSymbolType.Identifier;[Bar];
        CSharpSymbolType.WhiteSpace;[    ];
