Directive block - Gen<None> - 18 - (0:0,0)
    Transition span - Gen<None> - [@] - SpanEditHandler;Accepts:None - (0:0,0) - Tokens:1
        CSharpTokenType.Transition;[@];
    MetaCode span - Gen<None> - [addTagHelper] - SpanEditHandler;Accepts:None - (1:0,1) - Tokens:1
        CSharpTokenType.Identifier;[addTagHelper];
    Markup span - Gen<None> - [ ] - SpanEditHandler;Accepts:None - (13:0,13) - Tokens:1
        CSharpTokenType.WhiteSpace;[ ];
    Code span - Gen<AddTagHelper:{"Foo;"Foo;;} [RZ1000(14:0,14 [1] ), RZ1019(14:0,14 [4] ), RZ1036(14:0,14 [4] )]> - ["Foo] - SpanEditHandler;Accepts:AnyExceptNewline - (14:0,14) - Tokens:1
        CSharpTokenType.StringLiteral;["Foo];RZ1000(14:0,14 [1] )
