Merge key and value of array index [duplicate]

PHP Snippet 1:

$arr = ['foo'=>'bar','baz'=>'bat'];
$combine = array_map(fn($k, $v) => "$k: $v", array_keys($arr), array_values($arr));
print_r($combine);

PHP Snippet 2:

Array
(
    [0] => foo: bar
    [1] => baz: bat
)

PHP Snippet 3:

$arr = [ 'foo' => 'bar', 'baz' => 'bat' ];

$result = [];

array_walk($arr, function ($value, $key) use (&$result) {
  $result[] = "$key: $value";
});