It is php code. The input is already given. Need the php output that it is asking.

Given an associative array:

$input = [

['key'=>'njit', 'value'=>'awesome'],

['key'=>'njit', 'value'=>'best return'],

['key'=>'njit', 'value'=>'and small'],

['key'=>'Rutgers', 'value'=>'big'],

['key'=>'Rutgers', 'value'=>'highly ranked'],

['key'=>'Princeton', 'value'=>'best in US'],

['key'=>'Rutgers-newark', 'value'=>'cool'],

];

Please write some php code to transform the above given array to the following format:

$output = [

'njit'=>['awesome','best return','and small'],

'Rutgers'=>['big','highly ranked'],

'Princeton'=>'best in US',

'Rutgers-newark'=>'cool'

]