DSL EXPRESSION:
$x = (NF + NR) * 7; $y = OFS . $y . "hello"


AST:
"block" [tt:block] [nt:StatementBlock]
    "=" [tt:equals] [nt:Assignment]
        "$x" [tt:field_name] [nt:DirectFieldValue]
        "*" [tt:op_star] [nt:Operator]
            "+" [tt:op_plus] [nt:Parenthesized]
                "+" [tt:op_plus] [nt:Operator]
                    "NF" [tt:ctx_NF] [nt:ctx_NF]
                    "NR" [tt:ctx_NR] [nt:ctx_NR]
            "7" [tt:int_literal] [nt:int_literal]
    "=" [tt:equals] [nt:Assignment]
        "$y" [tt:field_name] [nt:DirectFieldValue]
        "." [tt:op_dot] [nt:DotOperator]
            "." [tt:op_dot] [nt:DotOperator]
                "OFS" [tt:ctx_OFS] [nt:ctx_OFS]
                "$y" [tt:field_name] [nt:DirectFieldValue]
            ""hello"" [tt:string_literal] [nt:string_literal]

