DSL EXPRESSION:
$x = ($a + $b) + $c; $y = $a + ($b + $c); $z = $a + ($b)+ $c


AST:
* statement block
    * assignment "="
        * direct field value "x"
        * operator "+"
            * operator "+"
                * direct field value "a"
                * direct field value "b"
            * direct field value "c"
    * assignment "="
        * direct field value "y"
        * operator "+"
            * direct field value "a"
            * operator "+"
                * direct field value "b"
                * direct field value "c"
    * assignment "="
        * direct field value "z"
        * operator "+"
            * operator "+"
                * direct field value "a"
                * direct field value "b"
            * direct field value "c"

