how to change the  $arr  array into the structure of  $newArr  
$arr = [
    [
        "id" => "1",
        "name" => "a",
        "attr" => "",
        "val" => "10"
    ],
    [
        "id" => "1",
        "name" => "a",
        "attr" => "",
        "val" => "11"
    ],
    [
        "id" => "2",
        "name" => "b",
        "attr" => "",
        "val" => "12"
    ],
    [
        "id" => "2",
        "name" => "b",
        "attr" => "",
        "val" => "13"
    ],
];
Array structure to be changed:
$arr = [
    [
        "id" => "1",
        "name" => "a",
        "info" => [
             ["attr" => "", "val" => "10"]
             ["attr" => "", "val" => "11"]
        ]
    ],
    [
        "id" => "2",
        "name" => "b",
        "info" => [
             ["attr" => "", "val" => "12"]
             ["attr" => "", "val" => "13"]
        ]
    ]
];
						