DSL EXPRESSION:
$x = 1 ? 2 : 3 ? 4 : 5


AST:
* statement block
    * assignment "="
        * direct field value "x"
        * operator "?:"
            * int literal "1"
            * int literal "2"
            * operator "?:"
                * int literal "3"
                * int literal "4"
                * int literal "5"

