DSL EXPRESSION:
NR == 3 {$* = @v[$2]}


AST:
* statement block
    * cond block
        * operator "=="
            * context variable "NR"
            * int literal "3"
        * statement block
            * assignment "="
                * full record "$*"
                * array or map index access "[]"
                    * direct oosvar value "v"
                    * direct field value "2"

