[ 0 => [ 'a' => 123, 456 => [ 0 => 'bcd', ], ],]
[ 'result' => [ 'string' => 'a:2:{s:1:"a";i:123;i:456;a:1:{i:0;s:3:"bcd";}}', ], 'php_version' => '7.1.33 Linux x86_64',]