DSL EXPRESSION:
begin{begin{@x=1}}

AST:
"block" [tt:block] [nt:StatementBlock]
    "begin" [tt:kw_begin] [nt:BeginBlock]
        "block" [tt:block] [nt:StatementBlockInBraces]
            "block" [tt:block] [nt:StatementBlock]
                "begin" [tt:kw_begin] [nt:BeginBlock]
                    "block" [tt:block] [nt:StatementBlockInBraces]
                        "block" [tt:block] [nt:StatementBlock]
                            "=" [tt:equals] [nt:Assignment]
                                "@x" [tt:oosvar_name] [nt:DirectOosvarValue]
                                "1" [tt:int_literal] [nt:int_literal]

