DSL EXPRESSION:
for ((k1,k2,k3), v in @*) {}

AST:
* statement block
    * multi-variable for-loop "for"
        * parameter list
            * local variable "k1"
            * local variable "k2"
            * local variable "k3"
        * local variable "v"
        * full oosvar "@*"
        * statement block

