将现有数组中的键/值对翻转到关联数组中，该关联数组允许在PHP中具有多个值的键

I need to basically flip an existing associate array into another associate array. It needs to contain the keys from the previous array as values and the values of the previous array as keys. Also, it needs to be able to contain multiple values for a single key.

Code:

 class Owner {
 public static function groupOwners($array)
 {
   //insert code
 }
 }
 $array = array(
  "Input.txt" => "Bob",
  "Code.py" => "Steve",
  "Output.txt" => "Bob"
 );
 var_dump(Owner::groupOwners($array));

The output generated is to be:

["Bob"] => ["Input.txt, Output.txt"], ["Steve"] => ["Code.py"]

You didn't show an attempt but I'm bored:

foreach($array as $key => $val) {
    $result[$val][] = $key;
}