DSL EXPRESSION:
$z = [5,6,7,8,9][1]


AST:
* statement block
    * assignment "="
        * direct field value "z"
        * array or map index access "[]"
            * array literal "[]"
                * int literal "5"
                * int literal "6"
                * int literal "7"
                * int literal "8"
                * int literal "9"
            * int literal "1"

