Permutations

---

examples/arrays/permutations.cr

numbers = [1, 2, 3]
numbers.permutations.each { |num|
  puts num
}

[1, 2, 3]
[1, 3, 2]
[2, 1, 3]
[2, 3, 1]
[3, 1, 2]
[3, 2, 1]