use v5;
use List::AllUtils qw(partition_by);
my %h = partition_by { ($_ - 1) % 4 } 1..14
# (0 => [1, 5, 9, 13], 1 => [2, 6, 10, 14], 2 => [3, 7, 11], 3 => [4, 
+8, 12])

use v6;
my %h = roundrobin((1..14).rotor(4, :partial)).kv
# {0 => [1, 5, 9, 13], 1 => [2, 6, 10, 14], 2 => [3, 7, 11], 3 => [4, 
+8, 12]}
[download]