DOMImplementation
object(DOMImplementation)#1 (0) {
}
string(29) "O:17:"DOMImplementation":0:{}"
object(DOMImplementation)#2 (0) {
}
array(4) {
  [0]=>
  string(11) "__construct"
  [1]=>
  string(14) "createDocument"
  [2]=>
  string(18) "createDocumentType"
  [3]=>
  string(10) "hasFeature"
}
================
A_DOMImplementation
object(A_DOMImplementation)#3 (1) {
  ["___x"]=>
  NULL
}
string(44) "O:19:"A_DOMImplementation":1:{s:4:"___x";N;}"
object(A_DOMImplementation)#4 (1) {
  ["___x"]=>
  NULL
}
array(4) {
  [0]=>
  string(11) "__construct"
  [1]=>
  string(14) "createDocument"
  [2]=>
  string(18) "createDocumentType"
  [3]=>
  string(10) "hasFeature"
}