DSL EXPRESSION:
begin { @u[2] = @v[1] }


AST:
"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]
                    "[]" [tt:[]] [nt:ArrayOrMapIndexAccess]
                        "@u" [tt:oosvar_name] [nt:DirectOosvarValue]
                        "2" [tt:int_literal] [nt:int_literal]
                    "[]" [tt:[]] [nt:ArrayOrMapIndexAccess]
                        "@v" [tt:oosvar_name] [nt:DirectOosvarValue]
                        "1" [tt:int_literal] [nt:int_literal]

