public function dataProviderForIsNotSquare() { return [[[[1, 2]]], [[[1, 2, 4], [2, 3, 5]]], [[[1, 2, 3, 5], [4, 5, 6, 5], [7, 8, 9, 5]]], [[[1, 2, 3], [4, 5, 6], [7, 8, 9], [1, 2, 3]]]]; }