DSL EXPRESSION:
$x =  1 *  2 + 3


AST:
"block" [tt:block] [nt:StatementBlock]
    "=" [tt:equals] [nt:Assignment]
        "$x" [tt:field_name] [nt:DirectFieldValue]
        "+" [tt:op_plus] [nt:Operator]
            "*" [tt:op_star] [nt:Operator]
                "1" [tt:int_literal] [nt:int_literal]
                "2" [tt:int_literal] [nt:int_literal]
            "3" [tt:int_literal] [nt:int_literal]

