sub Ȧ {?$_&&!$_».List.flat».List.flat.grep: *==0} for (True => [ [1,], [10,], [[,],], [[[[1,],],],], [[], [1], [1, 2]], [[1], [1, [2]], [1, [2, [3]]]], [[8], [8, [9]], [8, [9, [10]]]] ], False => [ [,], [0,], [0, -1], [-1, 0], [[[[0,],],],], [[0,], [1, 2], [3, 4, 5]], [[8,], [8, [9]], [8, [9, [1, 0]]]], [-1, 0, 0, 0] ]).Hash.kv -> $expected, @tests { say "Expected: $expected"; for @tests -> @list { say "\t{@list.raku} -> {Ȧ(@list)}" } }