-- main.mcl --
import "fmt"

$list1 = ["a", "b", "c",]
$list2 = [42, 13, -4,]

for $index1, $value1 in $list1 {
	for $index2, $value2 in $list2 {

		$s = fmt.printf("%s is %d", $value1, $value2)
		test [$s,] {}
	}
}

-- OUTPUT --
Vertex: test[a is 42]
Vertex: test[b is 42]
Vertex: test[c is 42]
Vertex: test[a is 13]
Vertex: test[b is 13]
Vertex: test[c is 13]
Vertex: test[a is -4]
Vertex: test[b is -4]
Vertex: test[c is -4]