Nested

var arr = 10.of{ 10.of{ pick(1..20) } }

for row in arr {
    for num in row {
        "%3d".printf(num)
        num == 20 && goto :OUT
    }
    print "\n"
} @:OUT

print "\n"

Output:

  9 17 14 17 17  7  1  3  9 18
  1 12  1 19  9  5  1 17 19  3
 17  2 18 12 15 10  8 13 13 14
 12 16 13 13  2 11  3 15  2  4
 15 15  8 11  5  2  1 16  8 13
 17  3  1  1  8 12  4 20