$index_array = array(1, 2, 3);
$assoc_array = array(1 => 'one', 2 => 'two');

$variation_array = array(
  'empty array' => array(),
  'int indexed array' => $index_array,
  'associative array' => $assoc_array,
  'nested arrays' => array('foo', $index_array, $assoc_array),
  );