30       var_dump($this->getOld()->getPrefixes());
31       var_dump($this->getNew()->getPrefixes());
32
33       $remove = array_diff($this->getOld()->getPrefixes(), $this->getNew()->getPrefixes());
34       $add    = array_diff($this->getNew()->getPrefixes(), $this->getOld()->getPrefixes());
35
36       var_dump($remove);
37       var_dump($add);

array(4) {
  [0]=>
  string(4) "7495"
  [1]=>
  string(4) "7499"
  [2]=>
  string(4) "7495"
  [3]=>
  string(4) "7499"
}
array(2) {
  [0]=>
  string(4) "7495"
  [1]=>
  string(4) "7499"
}
array(0) {
}
array(0) {
}