009+ Fatal error: Uncaught TypeError: Argument 2 passed to array_filter() must be callable, string given in %s/array_filter_error.php:32
010+ Stack trace:
011+ #0 %s/array_filter_error.php(32): array_filter(Array, 'even')
009- Warning: array_filter() expects parameter 2 to be a valid callback, function 'even' not found or invalid function name in %s on line %d
010- NULL
011- Done
012+ #1 {main}
013+ thrown in %s/array_filter_error.php on line 32